UNIVERSITY  OF  CALIFORNIA 

ANDREW 

SMITH 

HALLIDIL: 


COMPEND  OF 


Mechanical  Refrigeration 


A    COMPREHENSIVE   DIGEST    OF    APPLIED    ENERGETICS 
AND   THERMODYNAMICS    FOR    THE    PRAC- 
TICAL  USE   OF 


Ice  Manufacturers,  Cold  Storage  Men,  Contractors, 

Engineers,  Brewers,  Packers  and  Others 

Interested  in  the  Application  of 

Refrigeration. 


FIFTH  EDITION. 


BY  J.  E.  SIEBEL, 

Director  Zymotectinic  Institute,  Chicago, 


CHICAGO : 

H.   S.  RICH  &  Co. 
1903. 


=   : 


Entered  according  to  act  of  Congress  by 

H.  S.  RICH  &  CO., 

In  the  office  of  the  Librarian  of  Congress  at  Washington,  D.  CT 
1895, 1896, 1899, 1902  and  1903. 


All  rights  of  translation  reserved. 


PRESS  OP 
ICE  AND  REFRIGERATION 

CHICAGO. 


PREFACE. 


WHILE  in  the  third,  fourth  and  fifth  editions  of  the 
Compend  the  general  arrangements  of  matter  and  the 
manner  of  treatment  remain  the  same  as  in  the  first  and 
second  editions,  it  is  nevertheless  an  entirely  new  book. 
Not  only  that  the  contents  of  the  fifth  edition  covers 
nearly  one  hundred  and  fifty  pages  more  than  they  did 
in  the  first  edition,  but  also  much  of  the  former  matter 
has  been  entirely  rewritten  and  nearly  every  topic  has 
received  valuable  additions. 

This  will  be  especially  noticed  in  the  practical  chap- 
ters on  the  "Compressor  and  Its  Attachments,''  "Ice 
and  Distilled  Water  Making,"  "Cold  Storage,"  "Piping 
of  Rooms,"  "Insulation  and  Heat  Leakage,"  "Brewery 
Refrigeration,"  "Absorption  Machine,"  "Management  and 
Testing  of  Machines,"  etc.  On  "Liquefied  Air,  Its  Pro- 
duction and  Uses,"  and  on  "The  Carbonic  Acid  Machine" 
entirely  new  chapters  have  been  added.  The  cold  storage 
temperature  taWes  and  storage  rates  have  again  been  thor- 
oughly revised,  and  many  important  tables  and  many  prac- 
tical examples  on  various  topics  have  been  added  to  the 
book;  and  although  it  now  covers  over  four  hundred 
pages,  it  nevertheless  retains  its  convenient  shape,  equally 
well  adapted  for  pocket  and  table  use. 

Special  attention  has  been  given  to  the  preparation 
of  the  table  of  contents,  and  more  particularly  to  the 
topical  index,  which  contains  some  fifteen  hundred  refer- 
ences, so  that  whatever  has  been  said  in  the  book  on  any 
subject  can  be  readily  found  under  every  possible  appella- 
tion. 

Again,  the  hints  and  suggestions  kindly  offered  by 
the  engineering  fraternity  have  been  duly  utilized  in  the 
present  edition.  Still  many  imperfections  must  neces- 
sarily remain,  and  for  this  reason  the  author  solicits 
such  further  communications  and  criticism  as  may  tend 
to  render  the  work  of  the  greatest  possible  utility  to  the 
profession. 


116770 


PREFACE  TO  FIRST  EDITION. 


THE  object  for  which  this  book  has  been  compiled  is 
a  two-fold  one.  In  the  first  place  it  is  intended  to  pre- 
sent in  a  convenient  form  those  rules,  tables  and  formulae 
which  are  frequently  needed  by  the  refrigerating  en- 
gineer. In  the  second  place  it  is  an  attempt  to  present 
the  subject  in  a  simple  yet  systematic  manner,  so  as  to 
enable  the  beginner  to  acquire  a  more  or  less  thorough 
insight  into  the  matter  and  to  understand  the  technical 
terms  used  in  publications  on  the  subject. 

This  course  has  been  suggested  or  rather  prompted 
by  constant  inquiries  addressed  to  the  publishers,  and  in 
order  to  best  subserve  this  purpose  the  different  para- 
graphs and  chapters  have  been  framed  in  such  a  man- 
ner, that  while  each  paragraph  may  be  consulted  for  the 
individual  information  which  it  contains,  the  whole 
forms  a  continuous  chain  of  reading  matter  calculated  to 
digest  the  entire  subject  of  Energetics  and  Thermodynam- 
ics and  their  application  to  mechanical  refrigeration. 

Instead  of  making  the  futile  attempt  to  describe  the 
decorative  details  of  the  endless  varieties  of  machines 
and  appliances,  the  author  has  aimed  to  discuss  the  vari- 
ous methods  of  refrigeration  and  applications  thereof  for 
different  purposes  in  such  a  manner  as  to  enable  every 
engineer,  operator  and  owner  of  a  plant  to  thoroughly 
understand  all  the  vital  points  in  the  working  of  his 
machinery  and  in  the  handling  of  goods  for  cold  storage, 
in  the  making  of  ice,  in  the  refrigeration  of  breweries, 
packing  houses,  etc. 

In  this  way  it  is  thought  that  the  familiar  questions 
as  to  temperatures,  say  of  brine  and  storage  rooms,  as  to 
what  a  machine  is  able  to  do  under  given  conditions,  01 


PREFACE. 

what  it  might  be  made  to  do  under  others,  as  to  the  proper 
dimensions  of  different  parts,  and  most  other  problems 
relating  to  the  operation  of  refrigerating  works,  can  be 
readily  answered  by  turning  to  a  paragraph  or  a  table,  and 
in  cases  of  greater  accuracy  by  doing  some  plain  figuring. 

The  different  amounts  of  space  allotted  to  the  differ- 
ent systems  of  refrigeration  must  not  be  construed  into 
argument  for  or  against  the  merits  of  one  or  the  other 
system.  The  author  is  not  interested  in  any  one  system 
in  particular,  and  if  his  intention  to  be  strictly  impartial 
is  not  actually  carried  out  in  every  respect,  his  judgment 
rather  than  his  impartiality  should  be  impeached. 

As  regards  the  mathematical  treatment  of  the  sub- 
ject, it  had  to  be  strictly  elementary  and  without  the  use 
of  diagrams  to  subserve  the  desired  purpose  of  a  book  for 
ready  reference.  In  presenting  the  subject  on  this  basis  it 
has  been  the  special  object  of  the  author  to  have  the 
formula  as  plain  and  simple  as  they  could  be  made  with- 
out making  an  undue  sacrifice  in  regard  to  accuracy. 
This  is  especially  the  case  with  all  the  formulas  relating 
to  ammonia  refrigeration,  which  subject,  like  some  others, 
has  been  treated  altogether  on  the  basis  of  articles  pub- 
lished by  the  author  in  Ice  and  Refrigeration. 

In  order  to  further  enhance  the  usefulness  of  the 
book,  and  in  forced  recognition  of  the  fact  that  many 
practical  machinists  have  an  aversion  to  even  the  sim- 
plest kind  of  a  formula,  a  separate  appendix  has  been 
devoted  to  the  numerical  solution  of  a  number  of  varied 
examples,  which  it  is  thought  will  suffice  to  demonstrate 
that  the  formulae  in  these  chapters  can  be  handled  by 
any  one  versed  in  the  simplest  forms  of  common  figuring. 

Independent  of  the  strictly  practical  issues,  and  in 
pursuance  of  the  stated  objects  of  the  Compend,  it  has 
been  sought  to  give  so  much  of  an  elementary  discussion 
of  the  terms  and  definitions  of  the  science  of  energetics 
and  of  thermodynamics  in  particular,  that  its  perusal  will 
suffice  to  understandingly  master  the  technical  terms  in 


PREFACE. 

treatises  on  refrigeration  and  kindred  topics  in  Ice  and 
Refrigeration  and  other  publications. 

In  this  attempt  those  definitions  and  concepts  which 
are  of  more  recent  coinage  and  which  have  not  as  yet 
been  generally  accepted  in  text  books,  have  for  this  reason 
received  rather  more  attention  in  these  pages  than  their 
direct  relation  to  the  main  subject  would  seem  to  call  for 
at  first  sight. 

To  those  who  possess  the  required  practical  and  the- 
oretical knowledge,  the  book  will  doubtless  prove  a  wel- 
come companion,  as  it  contains  in  a  very  convenient  form 
a  prolific  array  of  useful  and  indispensable  tables,  and  a 
number  of  rules  which  are  not  usually  committed  to 
memory. 

Aside  from  the  works  quoted  in  Appendix  III.  the 
author  is  indebted  to  many  of  the  ice  machine  building 
fraternity  for  much  of  the  information  here  presented, 
and  he  may  also  be  allowed  to  mention  in  this  direction 
the  valuable  contributions  to  Ice  and  Refrigeration  by 
Wood,  Denton,  Jacobs,  Linde,  Sorge,  Starr,  Eichmond, 
St.  Clair,  Post,  Rossi,  Kilbourn,  Burns  and  others. 

There  naturally  must  be  many  imperfections  and 
shortcomings  connected  with  an  attempt  like  this,  and 
special  pains  have  been  taken  to  draw  attention  to  them 
in  the  body  of  the  book,  and  any  further  suggestions  or 
hints  in  this  direction  by  those  using  the  same  will  be 
thankfully  received  by  its  author  with  a  view  to  further 
improve  and  perfect  the  contents  of  this  publication. 


TABLE  OF  CONTENTS. 


PART  I.— GENERAL  ENERGETICS. 

CHAPTER  I.-MATTER. 

"MATTER— General  Properties  of  Matter,  Constitution,  Atoms, 
Molecules,  Solid,  Liquid,  Gaseous  Matter 5 

Body,  Mass,  Unit  of  Mass,  Mass  and.Weight,iMeasurement  of 
Space,  Density,  Specific  Weights.: 6 

Fundamental  Units,  Derived  Units,  C.  G.  S.  Units 6 

CHAPTER  II.— MOTION,  FORCE. 

MOTION.— Force,  Measurement  of  Force,  Dyne,  Gravitation, 
Molecular  Forces,  Cohesion  (table) 7 

Adhesion,  Chemical  Affinity, Work,  Unit  of  Work,  Foot-Pound, 
Time,  Power,  Horse-Power,  Velocity,  Momentum 8 

Inertia,  Laws  of  Motion,  Statics,  Dynamics  or  Kinetics 9 

CHAPTER  III.— ENERGY. 

ENERGY.— Visible  Energy,  Kinetic  Energy,Potential  Energy, 
Molecular  Energy • 9 

C.  G.  S.  Unit  of  Energy,  the  Erg,  the  Dyne  Centimeter,  Con- 
servation of  Energy,  Transformation  of  Energy 10 

Physics,  Subdivision  of  Physics,  Dissipation  of  Energy, 
Energy  of  a  Moving  Body,  Mechanisms 10 

CHAPTER  IV  —HEAT. 

HEAT.— Sources  of  Heat;  Ether,  RadiantJHeat  and  Light 11 

Temperature,  Thermometer,  Thermometer  Scales 12 

Comparison  of  Thermometer  Scales  (table ) 13 

Measuring  High  Temperatures 14 

Absolute  Zero,  Unit  of  Heat H 

C.  G.  S.  Unit  of  Heat,  Capacity  for  Heat,  Specific  Heat 1& 

Tables  on  Specific  Heat  of  Solids,  Liquids  and  Water  at  Dif- 
ferent Temperatures - 16-16 

Use  of  Specific  Heat,  Determination  of  Specific  Heat,  Tem- 
perature of  Mixtures 16 

Expansion  by  Heat  of  Solids  (table),  of  Liquids IT 

Expansion  of  Water  and  Liquids  (tables),  Transfer  of  Heat..    18 

Insulators  (table) 19 

Conduction   of   Heat,  Conductivity   of    Metals,  Radiation  of 

Heat,  Theory  of  Heat  Transfers,  Absorption  of  Heat 20 

Convection  of  Heat,  Complicated  Transfer,  Convection 23 

Comparative  Absorption  and  Radiation  (table) 25 

Condensation  of  Steam  in  Pipes,  Heat  Emitted  (tables) . . .24-2&-26 

Non-conductive  Coating  for  Steam  Pipes  (tables) 23-24 

Cooling  of  Water  in  Pipes  (tables) 24-25 

Transmission  of  Heat  through  Plates  from  Water  to  Water 

and  Steam  to  Water  (tables) 27-28 

Condensation  in  Pipes  Surrounded  by  Water,  Transmission 

of  Heat  through  Pipes  (tables) 29-30 

Latent  Heat,  Latent  Heat  of  Fusion  (tables),  Effect  of  Pres- 
sure on  Melting  Point,  Latent  Heat  of  Solution 31 

Frigorific  Mixtures  (table ) . 32 


lii  TABLE  OP  CONTENTS, 

HEAT  BY  CHEMICAL,  COMBINATION.— Elementary  Bodies, 
Chemical  Atoms,  Molecules., .* '.-. 33-34 

•Chemical  Symbols,  Atomicity,  Tables  of  Properties  of  Ele- 
ments, Generation  of  Heat. , .' .33-34 

Measure  of  Affinity,  Total  Heat  Developed,  Maximum  Prin- 
ciple, Expressions  for  Heat  Developed,  Heat  of  Combina- 
tion with  Oxygen  ( table ) , 35 

COMBUSTION.— Air  Required  in  Combustion,  Gaseous  Prod- 
ucts..   ; .^. i 36-37 

Heat  Generated,  Coal,  Coke,  Lignite 38 

Chimney  and  Grate ' % 39 

Heat  by  Mechanical  Mean's  , <.'...:....    3» 

CHAPTER  v.— FLUIDS,  GASES,  VAPORS. 

FLUIDS  IN  GENERAL.— Viscosity,  Pascal's  Law,  Buoyancy 
of  Liquids,  Archimedean  Principle,  Specific  Gravity  De- 
termination, Hydrometers 40 

Comparison  of  Hydrometers,  Specific  Gravity,  Twaddle, 
Baume"  and  Beck  (tables),  Pressure  of  Liquids 41 

Water  Pressure,  Surface  Tension  of  Liquids,  Velocity  of  Flow    42 

Flow  of  Water  in  Pipes,  Flow  through  Pipes,  Head  of  Water, 
.  Water  Power,  Hydrostatics  and  Dynamics 45 

CONSTITUTION  OF  GASES.— Pressure  and  Temperature, 
Boyle's  Law,  Mariotte's  Law,  St.  Charles  Law,  Unit  of 
Pressure,  Absolute  and  Gauge  Pressure ........ 44 

Comparison  of  British  and  Metrical  Barometer,  Action  of 
Vacuum,  Mano-Meters,  Gauges,  Weight  of  Gases..., 45 

Mixture  of  Gases,  Dalton's  Law,  Buoyancy  of  Gases,  Lique- 
faction of  Gases,  Heat  of.  Compression,  Critical  Tempera- 
ture, Critical  Pressure,  Critical  Volume ; & 

•Table  of  Critical  Data,  Specific  Heat  of  Gases  (table) 47 

Isothermal   Changes,  Adiabatic  'Changes,  Free  Expansion, 

*       Latent  Heat  of  Expansion,  Volume  and  Pressure 48 

Perfect  Gas,  Absolute  Zero  Again,  Velocity  of  Sound  Friction 
of  Gas  in  Pipes,  Absorption  of  Gases 49-50 

VAPORS.— Saturated  Vapor,  Dry  or  Superheated  Vapor,  Wet 
Vapor,  Tension  of  Vapors ; .  . ; • 50 

Vaporization,  Ebullition,  Boiling  Point,  Variation  of  Boiling 
Points,  Retardation  of  Boiling,  Latent  Heat  of  Vaporiza- 
tion  ... . ......'...  51 

Befrigerating  Effects,  Liquefaction  '  of  Vapors,  Distilling, 
Condensation,,  Compression,  Dalton's  Law  for  Vapors, 
Vapors  from  Mixed  Liquids,  Sublimation,  Dissociation. . . .  52 

.CHAPTER  VI.— MOLECULAR  DYNAMICS. 

MOLECULAR  KINETICS.— Rectilinear  Motion  of  Molecules, 
Temperature  of  Gases,  Pressure  of  Gases,  Avogrado's 
Law ....; 63 

Velocity  of  Molecules  in  Gases,  Internal  Friction,  Total  Heat 

Energy  of  Molecules.... 54 

Law  of  Gay  Lussac,  Expansion  of  Gases,  Volume  and  Tem- 
perature  ....,» ,. . 56 

EQUATION  FOR  GASEOUS  BODIES— Equation  for  Perfect 
Gases,  Connecting  Volume,  Pressure  and  Temperature.. . .  55 

Van  der  Waal's  Universal  Equation  for  Gases : 5ft 

Critical  Condition,  of  Gases,  Critical  Data ,. . .  .66-51 

Application  of  Universal  Equation,  Molecular  Dimensions... 58-59 
Absolute  Boiling  Point,  Capillary  Attraction,  Gas  and  Vapor, 
Liq-uef action  of  Gases 60 

CHAPTER  VII.— THERMODYNAMICS. 

THERMODYNAMICS.-First  Law  of  Thermodynamics,  Sec- 
ond Law  of  Thermodynamics,  Equivalent  Units,  Mechan- 
ical Equivalent  of  Heat  ( J),  Second'Law  Qualified 61 


TABLE  OP  CONTENTS.  ill 

Conversion  of  Heat  into  Work,  Continuous  Conversion,  Work- 
ing Substance.  Working  Medium,  Molecular  Transforma- 
tion of  Heat  into  Work,  Work  Done  by  Gas  Expanding 
against  Resistance,  Vacuum,  Heat  Energy  of  Gas  Mixtures    62 
Dissipation  of  Energy,  Adiabatic  Changes,  Adiabatic  Com- 
pression,  Adiabatic   Expansion,   Reversible  Changes   or 
Conversions,  Isothermal  Changes,  Isothermal  Compression    63 
Maximum   Conversion,  Continuous  Conversion,   Passage   of 
Heat,  Its  Ability  to  Do  Work  (Proportional  to  Differences 

in  Temperature) . ., 64 

Requirements  for  Continuous  Conversion,  Working  Medium, 
Boiler  or  Generator,  Refrigerator  or  Condenser,  Compen- 
sation for  Lifting  Heat . .64-to 

Components  of  Heat  Changes,  Internal  and  External  Work/ . 

Maximum  Continuous  Conversion  of  Heat 65 

CYCLE  OF  OPERATIONS.— Reversible  Cycle,  Ideal  Cycle....    66 

Ideal  Cycles  Have  the  Same  and  the  Maximum  Efficiency 66 

Influence  of  Working  Fluid,  Rate  of  Convertibility  of  Heat, 

Carnot's  Cycle. 67 

Synopsis  of  Proof  of  Second  Law 67-68 

Efficiency  of  Ideal  Cycle,  Description  of  Carnot's  Cycle 68-69 

Heat  Engines,  Available  Effect  of  Heat 70 

Consequences  of  Second  Law,  Absolute  Zero  of  Temperature.70-7l 
Ideal  Refrigerating  Machine,  Efficiency  and  Fall  of  Heat.... 71-72 
COMPENSATED  TRANSFER  OF  HEAT.— Uncompensated 

Transfer,  Entropy,  Latent  and  Free  Energy 72- 

Future  Condition  of  Universe,  Changes  of  Entropy 73 

Increase  of  Entropy,  Origin  of  Heat  Energy 74 

SPECIFIC  HEAT  OF  GASES. -At  Constant  Volume,  at  Con- 
stant Pressure,  Components  of  Specific  Heat  of  Gases.. 75-76 

AIR  THERMOMETER.— Thermodynamic  Scale 76 

Heat,  Weight,  Entropy,  Thermodynamic  Function,  Carnot's 

Function,  the  Constant  of  the  Gas  Equation  (R ) 77 

Isentropic  Changes,  Latent  Heat  and  Entropy , ,.' 77 

CHAPTER  VIII.— MODERN  ENERGETICS. 

NATURE  OF  MASS.— System  of  Energetics,  New  Definition 
of  Energy,  Classification  of  Energy,  Mechanical  Energy, 
Heat,  Electric  and  Magnetic  Energy,  Chemical  or  Internal 
Energy,  Radiated  Energy 78 

Mechanical  Energy,  Kinetic  Energy,  Energy  of  Space,  Energy 
of  Distance  ( force ),  Energy  of  Surface,  Energy  of  Volume .  78 

Factors  of  Energy,  Intensity  Factor,  Capacity  Factor,  Applied 
to  Various  Forces  of  Energy,  Dimensions  of  Energy 79 

The  Intensity  Principle,  Compensation  of  Intensities,  Differ- 
ences of  Intensities,  Regulative  Principle  of  Energy,  Maxi- 
mum Amount  of  Transformation,  State  of  Equilibrium..  80 

Artificial  and  Natural'.Transf  ers,  Artificial  Equilibrium,  Dissi- 
pation of  Energy,  Radiant  Energy 81 

Transformation  of  Energy,  Reversible  Changes,  Irreversible 
Changes,  Perpetual  Motion  of  First  and  Second  Order,  Con- 
servative System 82 

Continuous  Conversion  of  Energy,  Maximum  Convertibility, 
Intensity  of  Principle,  Criterion  of  Changes 83 

Justification  of  Modern  Concepts,  Uniform  Units  of  Energy, 
Change  of  Absolute  Zero , 84 

PART  II.— PRACTICAL  APPLICATION.  • 

CHAPTER  I.— REFRIGERATION  IN  GENERAL. 

MEANS  FOR  PRODUCING  REFRIGERATION.— Classifica- 
tion of  Methods,  Air  Machines,  Windhausen  Machine 85 


IV  TABLE  OF  CONTENTS. 

Freezing  Mixtures,  Ice  Machines,  Construction  of  Machines, 
Vaporization,  Vacuum  and  Absorption  Machines  86 

Continuous  Absorption  Machine,  the  Compression  Machine 
Cycle  of  Operation , 87 

AMMONIA  MACHINES,  —  Qualifications  of  Ammonia  for 
Refrigerating  Purposes,  Perfect  Compression  System,  the 
Reversible  Cycle  of  Operations,  Work  to  Lift  Heat 88 

Formula  Expressing  Work,  Defect  in  Cycle,  Choice  of  Circu- 
lating Medium,  Discussion  of  Essential  Qualities  of  Differ- 
ent Refrigerating  Liquids  ( table)  ...*..,., 89 

Comparison  of  Ammonia,  Sulphurous  Acid  and  Carbonic  Acid 
for  Refrigeration,  Size  of  Ice  Making  Machines,  Ex- 
pressions for  Capacity,  Refrigerating  and  Ice  Making 
Capacity,  Various  Uses  of 'Refrigeration 89-90 

CHAPTER  II.— PROPERTIES  OF  AMMONIA. 

FORMS  OF  AMMONIA.— Anhydrous  Ammonia,  Composition 
and  Decomposition  of  Same,  Compressibility  and  Com- 
bustibility, Non-Explosiveness  of  Ammonia 91 

Handling  of  Drums  Containing  Ammonia,  Suffocating  Proper- 
ties of  Same,  Pressure  and  Temperature  of  Saturated 
Ammonia,  Vapor  Density  of  Amnionia  and  Volume  of 
Vapor,  Specific  Heat  -of  Liquid  and  of  Vapor  (Negative 
Specific  Heat) .:...............  92 

Specific  Volume  of  Liquid  Ammonia,  Latent  Heat  of  Evapora- 
tion, External  Heat,  Weight  of  Ammonia  Liquid  and  Vapor.  93 

Woo&s  Table  for  Properties  of  Saturated  Ammonia  Vapor. T. .   '94 

Van  der  Wall's  Formula  Applied  to  Ammonia,  Values  for 
Pressure  of  Saturated  Ammonia  by  this  Formula 95 

Superheated  Amnionia  Vapor,  Formulae  for  Superheated 
Vapor,  Relation  of  Volume,  Temperature  arid  Pressure.  .96-97 

AMMONIA  LIQUOR.— Strengths  of  Solution  of  Ammonia 
(table),  Showing  Specific  Gravity  and  Degrees  Baume 97 

Siaar'*  Table,  Showing  Relations  between 'Pressure  and  Tem- 
perature of  Ammonia  Solutions  of  Different  Strengths.. 98-99 

Explanation  of  Baume"  Scales  or  Hydrometers,  Saturated 
Solution  of  Ammonia,  Tables  Showing  Percentage  of  Am- 
monia in  Saturated  Solution  at  Different  Temperatures,  100 -101 

Heat  Generated  by  the  Absorption  of  Ammonia,  Formula  for 
Calculating  the  Same • .101-102 

Sim's  Table,  Showing  the  Solubility  of  Ammonia  in  Water  at 
Different  Pressures  and  Temperatures 102 

Tests  for  Ammonia,  Boiling  Point  Test,  Nessler's  Reagent, 
Different  Systems  of  Ammonia  Refrigeration 103-104 

CHAPTER  III.— WATER,  STEAM,  ETC. 

PROPERTIES  OF  WATER.— Composition,  Formation  of  Ice, 
Freezing  Point  Depressed  by  Pressure.  Properties  of  Ice, 
Steam,  Volume  of  Steam,  Pressure  of  Saturated  Steam. ..  105 
Total  Heat  in  Steam,  Latent  Heat  of  Vaporization,  Externaf 
Latent  Heat,  Internal  Latent  Heat,  Specific  Heat  of  Water 
and  of  Steam,  Negative  Specific  Heat  of  Steam,  Specific 

Heat  of  Ice,  Specific  Volume  of  Steam 106-107 

Table  Showing  Properties  of  Saturated  Steam 107 

Volume  and  Weight  of  Water  at  Different  Temperatures 108 

PRODUCTION  OF  STEAM.— Work  Done  by  Steam,  Heating 

Area  of  Boiler,  Priming 108 

Amount  of  Priming,  Flow  of  Steam  through  Pipes 109 

HYGROMETRY.— Air  Saturated  with  Moisture,  Hygrometric 
State  of  Atmosphere,  Absolute  Moisture,  Dew  Point, 
Determination  of  Moisture,  Wet  and  Dry  Bulb  Thermo- 
meter........   110 

Maximum  Tension  of  Aqueous  Vapor,  Table  Showing  Tension 

of  Vapor,  Drying  Air,  Vaporization  of  Water  into  Air..  11 1-113 
Purity  of  Water. 113 


TABLE  OF  CONTENTS.  V 

CHAPTER  IV.— THE  AMMONIA  COMPRESSION  SYSTEM. 
GENERAL  FEATURES.— The  System  a  Cycle,  the  Compressor.  114 

Refrigerating  Effect  of  the  Circulating  Medium  in  General  and 
of  Ammonia  in  Particular : ...115 

Work  of  Compressor  per  Pound  of  Ammonia  Circulated 115 

Heat  to  Toe  Removed  in  the  Condenser,  Amount  of  Superheat- 
ing, Counteracting  Superheating,  Amount  of  Ammonia 
Required  to  Prevent  Superheating 116 

Net  Theoretical  Refrigerating  Effect  of  One  Pound  of  Am- 
monia, Volume  of  Compressor,  Cubic  Capacity  of  Com- 
pressor (per  Minute),  Clearance  of  Compressor 117 

Formula  for  Clearance,  Refrigerating  Capacity  of  Compressor 
in  Tons  of  Refrigeration  and  in  Thermal  Units 118 

Ammonia  Passing  the  Compressor,  Net  Refrigerating  Ca- 
pacity   119 

Horse  Power  of  Compressor,  Size  of  Compressor  for  a  Given 
Refrigerating  Duty. —  119 

Reduced  Refrigerating  Duty,  Revolutions  and  Piston  Area —  120 

Useful  and  Lost  Work  of  Compressor,  Determination  of  Lost 
Work,  Indirect  Determination  of  Actual  Work 120-121 

Horse  Power  of  Compressor  Engine,  Water  Evaporated  in 
Boiler,  Coal  Required . 121-122 

Efficiency  of  Compressor : 122 

DIFFERENT  KINDS  OF  COMPRESSORS.-The  Linde  Com- 
pressor   . —  123 

The  De  La  Vergne  Compressor,  the  Water  Jacket  Compressor  124 

Tables  Showing  the  Relation  between  the  Volume  of  Ammonia 
Gas  Passing  the  System  and  the  Theoretical  Refrigeration 
under  Different  Back  and  Condenser  Pressures 124-125 

The  St.  Glair  Compound  Compressor,  Amount  of  Water  for 
Counteracting  Superheating 125 

The  By-Pass,  the  Oil  Trap ]26 

THE  CONDENSER.— Submerged  Condenser,  Amount  of  Con- 
denser. Surf  ace,  Empirical  Rules  and  Formulae 126-127 

Amount  of  Cooling  Water,  Rule  and  Empirical  Formulas, 
Economizing  Cooling  Water 128 

Device  for  Economizing  Cooling  Water,  Using  Same  for  Boiler 
Feeding,  Open  Air  Condenser,  Pipe  Required  for  Same 129 

Empirical  Rule  for  Piping,  Water  Required,  Condenser 
Pressure,  Liquid  Receiver 130 

Dimensions  of  Condenser,  Forecooler,  Purge  Valve,  Duplex 
Oil  Trap,  Wet  and  Dry  Compression 131-133 

Expansion  Valve,  Expansion  of  Ammonia,  Direct  and  Indirect 
Expansion,  Size  of  Expansion  Coils,  Piping  Rooms,  Usual 
Pipe  Sizes,  Circumstance  Governing  Amount  of  Pipe ...  134-135 

Transmission  of  Heat  or  Refrigeration  through  Pipes,  Discus-    • 
sion  of  the  Problems  Involved,  Practical  Rules  for  Piping.  135 

Scope  of  Rules  for  Piping,  Comparative  Dimensions  of  Pipe..  I3tf 

Brine  System,  Size  and  Amount  of  Pipes  in  Brine  Tank,  Pipe 
for  Brine  Circulation,  General  Empirical  Rule,  Rule  for 
Laying  Pipes,  Table  for  Equalizing  Pipes 137-138 

Table  Showing  Capacity  of  Single- Acting  Pumps 139 

The  Brine  Pump,  Preparation  of  Brine,  Table  Showing  Prop- 
erties of  Solutions  of  Salt,  Strength  of  Brine 140 

Rules  for  Calculating  Strength  of  Brine,  Points  Governing 
Strength  of  Brine °  141 

Salometer  and  Substitutes  for  Same,  Table  Showing  Specific 
Gravity  of  Salt  Solutions  and  Corresponding  Hydrometer 
Degrees,  Chloride  of  Calcium  for  Brine  Preparation  Table 
Showing  Properties  of  Chloride  of  Calcium  in  Solutipn.  142 

Brine  Circulation  vs.  Direct  Expansion,  the  Dryer  Liquid 
TraP- 142-14? 


Vi  .  TABLE  OF  CONTENTS. 

CHAPTER  V.— ICE  MAKING  AND  STORING. 

SYSTEMS  OF  ICE  MAKING.-Can  and  Plate  System,  Ice 
Making  Capacity  of  Plant,  Size  of  Cans  in  Can  System, 

Temperature  for  Freezing 144 

Dimensions  of  Ice  Making  Tanks  (table) 145 

Time  for  Freezing,  Amount  of  Pipe  in  Freezing  Tank 146 

Arrangement  of  Brine  Tank,  Size  of  Brine  Tank 14T 

The  Brine  Agitator,  Harvesting  Can  Ice,  Hot  Well 148 

Comparison  of  Plate  and  Can  System,  Size  of  Plates,  Time  for 

Freezing,  Harvesting  Plate  Ice,  Storage  of  Artificial  Ice..  149 
Ice  for  Storage,  Construction  of  Storage  Houses  for  Ice,  Ante- 
Room  in  Ice  Storage  House,  Equivalent  of  Ton  of  Ice  in 
Cubic  Feet,  Refrigerating  Ice  Houses,  Rule  for  Same ......  150 

Packing  Ice,  Withdrawal  and  Shipping  Ice,  Selling  of  Ice..  151-152 
Weight  and  Volume  of  Ice,  Cost  of  Ice,  Coal  for   Making 

Ice v 153-155 

Skating  Rinks,  Quality  of  Ice ;  156 

WATER  FOR  MAKING  ICE.— Requirements  of  Same,  Clear 

Ice,  Boiling  and  Filtration  of  Water \: ......  157 

Distilled  Water,  Cooling  Water  Required  in  Distillation,  Size 
of  Condenser,  Discussion  of  Rules  on  Amount  of  Con- 
densing Surf  ace,  Filtration  of  Water 158 

Re  boiling  and  Filtering  Distilled  Water,  Cooling  the  Distilled 

Water,  Storage  Tank 159 

Intermediate  Filter,  Dimensions  of  Distilling  Plant,  Dimen- 
sions of  a  Ten-ton  Distilling  Plant,  Dimensions  of  a 

Thirty-ton  Distilling  Plant 160 

Skimmer,  Brine  Circulation,  Arrangem  ent  of  Plant 161 

Defects  of  Ice,  White  or  Milky  Ice,  White  Core.  Red  Core, 
Taste  and  Flavor  of  Ice,  Use  of  Boneblack  and  Fil- 
tration   162-164 

Number  of  Filters,  Rotten  Ice,  Purity  of  Water  Test 165-166 

Devices  for  Making  Clear  Ice,  the  Cell  System,  Remuner- 
abilityof  Artificial  Ice  Making 167 

CHAPTER  VI.— COLD  STORAGE. 

COLD  STORAGE.— Storage  Rooms,  Their  Construction  and 
Size,  Construction  of  Wood 168 

Construction  of  Brick  and  Tiles,  and  Other  Constructions..  169-173 

REFRIGERATION  REQUIRED  for  Storage  Rooms  Expressed 
in  Units  per  Cubic  Foot : . .  fi& 

Piping  Cold  Storage  Rooms,  Refrigeration  Required  Found 
by  Calculation,  Radiation  through  Walls,  Transmission  of 
Heat  through  Walls  (tables) 174-182 

REFRIGERATION  OF  GOODS  for  Cold  Storage,  Calculation 
of  Amount,  Specific  Heat  of  Victuals  (table)......., 182 

Calculation  of  Specific  Heat  of  Victuals,  Freezing  Goods  in 
Cold  Storage,  Refrigeration  Required 183 

Conditions  Obtaining  in  Cold  Storage,  Ventilation,  Moisture, 
Dry  Air  for  Cold  Storage,  Forced  Circulation 184-188 

COLD  STORAGE  TEMPERATURES.— Storing  Fruits,  Table 
Showing  Best  Temperature  for  Different  Fruits 188 

Storing  Vegetables,  Onions,  Pears,  Lemons,  Grapes,  Apples, 
Liquors,  etc 189-192 

Storing  Fish  and  Oysters  (table),  Freezing  Fish,  Storage  of 
Butter,  Cheese,  Milk,  Eggs  and  Similar  Products 193-195 

Miscellaneous  Goods  (Table  of  Storage  Temperatures),  Ven- 
tilation of  Rooms,  Lowest  Cold  Storage  Temperatures 196 

CHAPTER  VII.— BREWERY  REFRIGERATION. 

OBJECTS  OF  BREWERY  REFRIGERATION.— Cooling  Wort, 
Removal  of  Heat  of  Fermentation,  Storage  of  Beer.  Rough 
Estimate  of  Refrigeration,  Specific  Heat  of  Wort  (table)..  197 


TABLE  OF  CONTENTS.  vii\ 

PROCESS  OP  COOLING  WORT.— Cooling  Vat,  Tubular  Cooler, 
Refrigeration  Required  for  Cooling  Wort,  Simple  Rule  for 
Calculation  of  Same 198 

Size  of  Machine  for  Wort  Cooling,  Increased  Efficiency  of  Ma- 
chine in  Wort  Cooling 199 

HEAT  PRODUCED  BY  .  FERMENTATION.  —  Calculation  of 
Heat  of  Fermentation  in  Breweries,  Simple  Rule  for  Same  200 

Refrigeration  for  Storage  Rooms  Expressed  in  Units  per  Cubic 
Foot  and  per  Square  Foot  of  Walls,  Closer  Calculations.. .  201 

Different  Saccharometers,  Table  of  Comparison  of  Them 202 

Cooling  Brine  and  Sweet  Water,  Total  Refrigeration,  Distri- 
bution of  Fermentation,  Dimensions  of  Wort  Cooler 203 

Direct  Expansion  Wort  Cooler , 204 

Piping  of  Rooms  in  the  Brewery,  Amount  Required,  Temper- 
ature of  Rooms,  Heat  of  Fermentation  Allowed  for 204-206 

REFRIGERATION  FOR  ALE  BREWERIES.  —  Amount  Re- 
quired for  Wort  Cooling  and  for  Storage,  etc.  Rule  for 
Piping ..206-207 

Attemperators,  Chilling  of  Beer,  Brewery  Site,  Storage  of 
Hops.. 207-210 

Refrigeration  in  Malt  Houses,  Actual  Refrigerating  Installa- 
tion in  Breweries  of  Different  Capacities 211 

CHAPTER  VIII.—  REFRIGERATION  FOR  PACKING  HOUSES, 
ETC. 

AMOUNT  OF  REFRIGERATION  REQUIRED.  — Theoretical 
Calculation  of  Same,  Practical  Rules  for  Same  (Units  per 
Cubic  Foot),  Calculation  per  Number  of  Animals,  Freez- 
ing of  Meaf  . 212 

Other  Methods  of  Calculating  Required  Refrigeration,  Rules 
for  Piping  of  Rooms  (Cubic  Feet  per  Foot  of  Pipe) 213 

Storage  Temperatures  for  Meat  (table),  Official  Views  on  Meat 
Storage,  Freezing,  etc. 214 

Best  Way  of  Freezing  Meat,  Circulation  of  Air  in  Rooms,  Ship- 
ping Meat,  Bone  Stink,  Defrosting  Meat,  etc 215-217 

Refrigeration  in  Oil  Works,  Oleomargarine,  Stearin  and  India 
Rubber  Works,- Dairy  Refrigeration,  Refrigeration  for 
Glue  Works,  Skating  Rinks,  etc 218-220 

Refrigeration  in  Chemical  Works 220-321 

Concentration  of  Sulphuric  Acid  by  Cold,  Decomposition  of 
Salt  Cake,  Pipe  Line  Refrigeration,  Refrigeration  and  En- 
gineering  ..., 221 

CHAPTER  IX.— THE  ABSORPTION  SYSTEM. 

CYCLE  OF.OPERATIONS.-A  Compound  Cycle,  Application 

of  First  Law  to  Same,  Equation  of  Absorption  Cycle 222 

Working  Conditions  of  System,  Heat  Added  in  Refrigeration.  223 
Heat  Introduced  by  Pump,  Amount  of  Rich  Liquor  to  be  Cir- 
culated  ; 224 

STRENGTH  OF  RICH  AND  POOR  LIQUOR.— Heat  Removed 

in  Condenser,  Heat.  Removed  in  Absorber 225 

Heat  of  Absorption,  Formula  to  Calculate  Same,  Table  Show- 
ing Same,  Heat  Introduced  by  Poor  Liquor 225-226 

Negative  Heat  Introduced  by  Vapor,  Heat  Required  in  Gener- 
ator, Work  by  Pump,  Anhydrous  Ammonia  Required.. ....  227 

HORSE  POWER  OF  AMMONIA  PUMP.  —  Amount  of  Con- 
denser Water  Required,  Water  Required  in  Absorber 228 

Economizing  Water,  Economizing  Steam,  Steam  Required.. .  229 

Actual  and  Theoretical  Capacity,  Heat  Used  in  Still. 230 

Expression  of  Efficiency,  Comparable  Efficiency  of  Compressor  231 
CONSTRUCTION  OF  ABSORPTION  MACHINE.-The  Gener- 
ator, the  Analyzer,  Battery  Generator,  Size  of  Still,  the 
Condenser '    232-233 


viii  TABLE  OF  CONTENTS. 

The  Rectifier,  Liquid  Receiver,  etc.,  the  Absorber,  the  Ex- 
changer   234-235 

The  Exchanger,  the  Heater,  the  Cooler,  the  Ammonia  Pump, 
Miscellaneous  Attachments , 236-237 

Overhauling  Plant.  Compression  vs.  Absorption,  Tabulated 
Dimensions 238-239 

CHAPTER  X.— THE  CARBONIC  ACID  MACHINE. 

General  Considerations,  Properties  of  Carbonic  Acid  Gas 
(table ),;.-. 240-241 

Construction  of  Plant,  Compressor,  Stuffing  Box,  Glycerine 
Trap,  Condenser,  Evaporator,  Safety  Valve 242-243 

Joints,  Strength  and  Safety,  Application  of  Machine,  Effi- 
ciency of  System 244-245 

Comparisons  of  Efficiency,  Practical  Comparative  Tests  ..  .246-247 

CHAPTER  XI.-OTHER  COMPRESSION  SYSTEMS. 

AVAILABLE  REFRIGERATING  FLUIDS. —Table  Showing 
Vapor  Tension  of  Ether,  Sulphur  Dioxide/Methylic  Ether, 
Carbonic  Acid,  Pictet  Liquid  and  Ammonia 248 

Methyl  and  Ethyl  Chloride  Machine  249 

REFRIGERATION  BY  SULPHUR  DIOXIDE.— Properties  of 
Sulphur  Dioxide 24& 

Table  of  Properties  of  Saturated  Sulphur  Dioxide  Gas,  Useful 
Efficiency,  Table  of  Comparison  of  Ammonia  and  Sulphur 
Dioxide  Plant 250 

ETHER  MACHINES.— Table  Showing  Properties  of  Saturated 
Vapor  of  Ether,  Practical  Efficiency  of  Ether  Machines. 25 1-252 

REFRIGERATION  BY  PICTET'S  LIQUID. —  Table  Showing 
Properties  of  Liquid,  Anomalous  Behavior  of  Pictet's 
Liquid,  Explanations  for  the  Anomaly 252-253 

Bluemcke  on  Pictet's  Liquid 253 

Mottay  and  Rossi's  System,  Cryogene,  Hydrocarbons  as  Re- 
frigerating Agents,  Acetylene,  Naphtha,  Chimogene,  etc..  264 

CHAPTER  XII.— AIR  AND  VACUUM  MACHINES. 

COMPRESSED  AIR  MACHINE.— Cycle  of  Operations,  Work 
of  Compression  of  Air 255 

Temperature  of  Air  after  Compression,  Cooling  of  Air  after 
Compression,  Amount  of  Water  Required,  Work  Done  by 
Expansion 256 

Temperature  after  Expansion,  Refrigeration  Produced,  Work 
for  Lifting  Heat,  Equation  of  Cycle 257 

Efficiency  of  Cycle,  Size  of  Cylinders,  Actual  Efficiency 258 

Experiments  Showing  Actual  Performance  on  Cold  Air  Ma- 
chines (table) 359 

Work  Required  for  Isothermal  Compression,  Work  Done  in 
Isothermal  Expansion,  Other  Uses  of  Compressed  Air, 
Table  Showing  Friction  by  Compressed  Air  in  Pipes 260 

Calculated  Efficiency  of  Compression  Air  Machine,  Limited 
Usefulness 261 

VACUUM  MACHINES. -  Refrigeration  Produced  by  Them, 
Efficiency  and  Size 261-263 

Compound  Vacuum  Machine,  Expense  of  Operating,  Objec- 
tions to  Sulphurous  Acid,  Southby's  Vacuum  Machine.. 262-263 

Southby's  Vacuum  Machine,  Operating  Same 284 

CHAPTER  XIII.— LIQUEFACTION  OF  GASES. 

Historical  Points,  Self-intensifying  Refrigeration 265 

Linde's  Simple  Method,  the  Rationale  of  Linde's  Device.... 266-267 

Variable  Efficiency,  Hampson's  Device,  Other  Methods 268 

Tripler's  Invention 269 


TABLE  OP  CONTENTS.  IX 

Uses  of  Liquid  Air 270-271 

Tabulated  Properties  of  Gases 272 

CHAPTER   XIV.— MANAGEMENT  OF  COMPRESSION  PLANT. 

INSTALLATION   OF    COMPRESSION    PLANT.— Proving  of 

Machine,  Pumping  a  Vacuum,  Charging  the  Plant 273 

Charging  by  Degrees,  Operation  of  Plant,  Detection  of  Leaks, 

Amount  of  Ammonia  Required,  Waste  of   Ammonia 275 

Ammonia  in  Case  of  Fire... 276 

Condenser  and  Back  Pressure  in  Different  Cases 277 

Table  Showing  Efficiency  of  Plant  under  Different  Conditions.  278 

Permanent  Gases  in  Plant,  Freezing  Back 279 

Origin  of  Permanent  Gases,  Clearance,  Valve  Lift 280 

Packing  Pistons,  Pounding  Pumps,  etc.,  Cleaning  Coils,  etc.. .  281 
Insulation,  Lubrication,  etc 282 

CHAPTER  XV.— MANAGEMENT  OF  ABSORPTION  PLANT. 

Management  and  Installation  of  Plant,  Ammonia  Required, 
Charging  of  Plant ; 283-284 

Recharging  Absorption  Plant,  Charging  with  Strong  Liquor 
and  Anhydrous  Ammonia 285 

Permanent  Gases  in  Plant 286 

Corrosion  of  Coils,  Kinds  of  Aqua  Ammonia  '. . . . . 287 

Leaks  in  Absorption  Plant,  Leak  in  Exchanger,  Leak  in  Rec- 
tifying Pans,  Strong  Liquor  Siphoned  over 288-289 

Tu.e  "Boil-over,"  Cleaning  the  Absorber,  Operating  the  Ab- 
sorber, Packing  Ammonia  Pump 290-292 

Economizing  Water,  Operating  Brine  Tank,  Leaks  in  Brine 
Tank... .293 

Top  and  Bottom  Feed  Coils,  Cleaning  Brine  Coils,  Dripping 
Ceiling,  Removing  Ice  from  Coils,  Cost  of  Refrigeration, 
Management  of  Other  Plants 294-295 

CHAPTER  XVI.— TESTING  OF  PLANT. 

Test  of  Plant,  Fitting  up  for  Test,  Mercury  Wells ,296 

The  Indicator  Diagram,  Maximum  and  Actual  Capacity...  297-301 
Commercial  Capacity,  Nominal  Compressor  Capacities  (table), 

Actual  Refrigerating  Capacity 302 

Friction  of  Compressor,  Heat  Removed  in  Condenser,  Maxi- 
mum Theoretical  Capacity,  Correct  Basis  for  Efficiency 


Calculation 


More  Elaborate  Test,  Table  Showing  Data  of  Tests  of  Com- 
pression Plant. 304 

Efficiency  of  Engine  and  Boiler,  Test  of  Absorption  Plant 305 

Table  Showing  Results  of  Test,  Estimate  and  Proposals 306 

Contracts,  How  Made 307 

Unit  of  Refrigerating  Capacity,  Test  of  Various  Machines  ...  308 

APPENDIX  L— TABLES,  ETC. 

Mensuration  of  Surfaces,  Polygons 309 

Properties  of  the  Circle,  Mensuration  of  Solids,  Polyhedrons.  310 

Table  of  Ammonia  Gas  ( Superheated  Vapor) . .  311 

Square  Roots  and  Cubic  Roots,  1-20.  (table ) 312 

Squares  and  Cubes  and  Roots,  1-100  (table) 313 

Areas  of  Circles,  Equivalents  of  Fractions  of  an  Inch. .  . .  314 

Tables  of  Logarithms,  1-999 315-316 

Rules  for  Logarithms '. 3^7 

Tables  of  Weights  and  Measures,  Troy  Weight,  Commercial 
Weight,  Apothecaries'  Weight,  Long  Measure  .  .  317 


TABLE  OF  CONTENTS. 

Inches  and  Equivalents  in  Feet,  Square  or  Land  Measure, 
Cubic  or  Solid  Measure,  Liquid  Measure,  Dry. Measure....  318 

The  Metric  Measure,  Measure  of  Length,  of  Liquids*  Etc 319 

Equivalents  of  French  and  English  Measure 319 

Specific  Gravity  and  Weight  of  Materials  (tables)..........  319-321 

Cpntents  of  Cylinders,  Table  of  Gallons 322 

Comparison  of  Metric  and  United  States  Weights  and  Meas- 
ures, Comparison  of  Alcoholometers 323 

Horse  Power  of  Belting  (table)  .Horse  Power  of  Shaftine 

(table) .7324 

Capacity  of  Tanks  in  Barrels  ( table) 325 

Table  of  Converting  Feet  of  Water  into  Pressure  per  Square' 

Inch,  Table  of  Horse  Power  Required  to  Raise  Water 32j5 

Table  Showing  Loss  of  Pressure  of  Water,  etc.,  while  Run- 
ning through  Pipes , ; , 327 

Flow  of  Steam  through  Pipes,  Horse  Powers  of  Boilers 328 

Tables  Shoeing  Properties  of  Saturated  Ammonia ; 329-331 

Humidity  and  Moisture  in  Air,  Latent  Heat  of  Fusion  and 

Volatilization :.. ...  332 

Cold  Storage  Rates .333-337 

Description  df  Two-flue  Boilers 337 

Useful  Numbers  for  Rapid  Approximations 338 

Weight  of  Castings , 338 

Solubility  of  Gases  in  Water , .339 

Dimensions  of  Double  Extra  Strong  Pipe 339 

Dimensions  of  Corliss  Engines 340 

Temperature  of  Different  Localities '.341 

Useful  Data  on  Liquids,  Measures,  etc : .341-342 

Table  of  Temperature,  Fahr.  and  Cels 343 

Specific  Gravity  Table  (Baum£) '.344 

Table  on  Chloride  of  Calcium 345 

Friction  of  Water  in  Pipes 346 

Units  of  Energy  (Comparison) 346-347 

Mean  Effective  Steam  Pressure .348-349 

Relative  Efficiency  of  Euel,  Table  on  Tension  of  Water  Vapor 

and  on  Boiling  Points 350 

Composition  of.  Water  Constituents  and  Table  on  Grains  and 
Grams, . .  351 

APPENDIX  II.— PRACTICAL  EXAMPLES. 

Introductory  Remarks,  Fortifying  Ammonia  Charge 358 

Numerical  Examples  on  Specific  Heat,  Evaporation  Power  of 
Coal,  Capacity  of  Freezing  Mixture,  .-....- 854 

Numerical  Examples  on  Permanent  Gases,  Examples  Show- 
ing Use  of  Gas  Equation ....355 

Work  Required  to  Lift  Heat,  Refrigerating  Effect  of  Sulphur- 
ous Acid,  Refrigerating  Capacity  of  a  Compressor 356 

Second  Method  of  Calculation  of  Compressor  Capacity,  Third 
Method  of  Calculation,  Cooling  Beer  Wort 857 

Heat  by  Absorption  of  Ammonia.  Water,  Rich  Liquor  to  be 
Circulated  in  Absorption  Machine  .  ^ 358 

Numerical  Calculation  of  Capacity  of  Absorption  Machine,, 
Heat  and  Steam  Required  for  Same 359 

Numerical  Examples  on  Cold  Storage,  by  Calculation,  by  an 
Appropriate  Estimate 360 

Calculation  of  Piping -Required , 361 

Numerical  Examples  on  Natural  Gas  with  Reference  to  Re- 
frigerating Purposes,  Temperature  of  Same  after  Expan- 
sion   36? 


TABLE  OP  CONTENTS.  xi 

Refrigerating  Capacity   of  Gas,  Work  Done  by  Expansion, 

Size  of  Expanding  Engine .• ^ 363 

Expansion  of  the  Gas  without  Doing  Work,  Refrigeration  Ob- 
tainable by  Expansion  Alone,  Calculation  of  Refrigerating 

Duty s 364-365 

Calculating  Ice  Making  Capacity,  Volume  of  Carbonic  Acid 

Gas < 366 

Horse  Power  of  Steam  Engine 307 

Calculation  of  Pump.. 368 

Motive  Power  of  Liquid  Air 3«9 

Moisture  in  Cold  Storage 370 

Carbonic  Acid  Machine 371 

APPENDIX  III.— LITERATURE  ON  THERMODYNAMICS,  ETC. 

a.  Books.  ... 372-373 

b.  Catalogues....;.... 374 

TOPICAL  INDEX 375-387 


MECHANICAL  REFRIGERATION. 


PART  I. 
GENERAL  ENERGETICS. 


CHAPTER  I.— MATTER. 

MATTER. 

Matter  is  everything  which  occupies  space  in  three 
directions,  and  prevents  other  matter  from  occupying 
the  same  space  at  the  same  time.  Matter  is  differen- 
tiated by  its  physical  and  chemical  properties,  color,  hard- 
ness, weight,  chemical  changeability,  etc. 

GENERAL  PROPERTIES  OF  MATTER. 

The  general  properties  of  matter  which  are  shared 
by  all  bodies  are  impenetrability,  extension,  divisibility, 
porosity,  compressibility,  elasticity,  mobility  and  inertia. 

CONSTITUTION  OF  MATTER. 

To  explain  the  different  properties  it  is  generally  as- 
sumed that  matter  is  ultimately  composed  of  infinitely 
small  particles  called  atoms,  which  aggregate  or  unite  to 
form  still  infinitely  small  groups  called  molecules.  At- 
tractive and  repulsive  forces  acting  between  the  atoms 
and  molecules,  and  their  respective  motions  are  made  to 
account  for  the  various  physical  and  chemical  phenomena. 

SOLID  MATTER. 

Matter  is  solid  when  the  molecules  possess  a  suffi- 
cient degree  of  immobility  to  insure  the  permanence  of 
shape. 

LIQUID  MATTER. 

If  the  molecules  of  a  body  are  sufficiently  movable  to 
allow  of  its  being  shaped  by  the  surrounding  vessel,  and 
if  the  same  can  be  easily  poured,  it  is  called  a  liquid. 

GASEOUS  MATTER. 

The  gaseous  state  of  matter  is  characterized  by  almost 
perfect  freedom  of  motion  of  the  molecules,  an  unlimited 
tendency  to  expand  and  a  great  compressibility.  The 
term  fluid  covers  both  the  liquid  and  the  gaseous  states. 


6  MECHANICAL  REFRIGERATION. 

BODY. 

A  body  is  a  limited  amount  of  matter. 

MASS. 

Mass  is  the  quantity  of  matter  contained  in  a  body. 

UNIT  OF  MASS. 

The  unit  of  mass  is  the  standard  pound,  which  in 
the  form  of  a  piece  of  platinum  is  preserved  by  the  gov- 
ernment. 

WEIGHT. 

Weight,  or  absolute  weight,  is  the  pressure  of  a  body 
exerted  on  its  support.  The  unit  of  weight  is  the  force 
necessary  to  support  one  pound  in  vacuo,  and  it  differs 
with  the  latitude,  as  the  gravity  or  the  earth's  attraction. 

MASS  AND  WEIGHT. 

The  relations  between  mass  and  weight  are  expressed 
by  the  equation  — 


in  which  M  stands  for  mass,  W  for  weight  and  g  for  the 
acceleration  caused  by  the  attraction  of  the  earth. 

MEASUREMENT  OF  SPACE. 

The  unit  of  measurement  of  space  is  the  cubic  foot 
and  its  subdivisions  (see  tables  of  weight  and  measures 

in  appendix,  etc). 

DENSITY. 

Equal  amounts  of  matter  do  not  necessarily  occupy 
the  same  space;  in  other  words,  the  density  of  different 
bodies  is  not  the  same  . 

SPECIFIC  WEIGHT. 

The  relative  density  of  different  bodies  is  expressed 
by  their  specific  gravity,  which  is  the  figure  obtained 
when  the  weight  of  a  body  is  divided  by  the  weight  of  an 
equal  volume  of  water. 

The  specific  weights  used  in  the  arts  and  industries 
are  given  in  tables  in  Appendix  1. 

FUNDAMENTAL  UNITS. 

The  fundamental  units  of  measurement  are  the  units 
of  distance,  time  and  mass. 

DERIVED    UNITS. 

From  the  fundamental  units  units  for  more  complex 
quantities  may  be  derived.  As  the  fundamental  units 
vary  in  different  countries,  the  derived  units  vary  also. 


FORCE.  7 

C.  G.  S.  UNITS. 

Besides  our  national  units,  the  units  derived  from 
the  French  or  metric  system  are  also  frequently  em- 
ployed. They  are  designated  as  the  centimeter-gramme- 
second  units;  abbreviated  C.  Gr  -S.  units,  and  are  also 
called  absolute  units. 


CHAPTER  II.— MOTION;-  FORCE. 

MOTION. 

The  removal  of  matter  from  one  place  to  another. 

FORCE. 

Any  cause  which  changes  or  tends  to  change  the 
condition  of  rest  or  motion  of  a  body  (in  a  straight  line). 

MEASUREMENT  OF  FORCE. 

Force  may  be  measured  by  the  change  of  momentum 
it  produces  in  a  second.  The  unit  of  force  is  a  dyne; 
it  is  based  on  the  metric  system,  and  represents  that 
force  which,  after  acting  for  a  second,  will  give  to  a 
gram  of  matter  a  velocity  of  one  centimeter  per  second. 

GRAVITATION. 

The  tendency  which  is  common  to  all  matter,  and 
according  to  which  all  bodies  mutually  attract  each  other 
with  an  intensity  proportional  to  their  masses  and  in- 
versely as  the  square  of  their  distances,  is  called  gravita- 
tion. 

The  force  of  the  earth  attraction  at  its  surface  is 
equivalent  to  981  dynes. 

MOLECULAR  FORCES. 

The  attraction  and  repulsion  which  exist  between 
the  minute  and  most  minute  parts  or  atoms  of  bodies 
are  often  referred  to  as  the  molecular  forces. 

COHESION. 

Cohesion  designates  the  attraction  existing  be- 
tween the  minute  parts  of  the  same  body;  and  for  solids 
it  is  measured  by  the  force  expressed  in  pounds  to  tear 
apart  by  a  straight  pull  a  rod  of  one  square  inch  area  of 
section.  This  measure  is  also  called  the  tenacity  of  a 
body  (tons). 

The  relative  tenacities  of  the  metals  are  given  ap- 
proximately in  the  table  below,  lead  being  taken  as  the 
standard. 

Lead 1.0       Castiron 7  to  12 

Tin  1.3       Wroughtiron    20to  40 

Zinc 2.0       Steel 40  to  143 

Worked  copper — 12  to  20 


S  MECHANICAL  REFRIGERATION. 

ADHESION. 

Adhesion  designates  the  attraction  between  the 
parts  of  dissimilar  bodies. 

CHEMICAL  AFFINITY. 

This  expression  generally  stands  for  the  relative  at- 
traction existing  between  the  smallest  particles  (atoms 
and  molecules)]of  different  substances,  which,  if  satisfied, 
brings  about  substantial  or  chemical  changes. 
WORK. 

Work  is  the  product  of  force  by  the  distance  through 
which  it  acts. 

The  unit  of  work  is  the  product  of  the  units  of  its 
factors,  force  and  space.  Useful  work  is  that  which 
brings  about  a  specific  useful  effect,  and  lost  work  is 
that  which  is  incidentally  wasted  while  producing  such 
effect. 

UNIT  OF  WORK. 

The  unit  of  work  is  the  foot-pound,  i.  je.,.the  work 
necessary  to  raise  one  pound  vertically  through  a  dis- 
tance of  one  foot.  One  pound  raised  vertically  through 
a  distance  of  ten  feet,  or  ten  pounds  raised  through  one 
foot,  or  five  pounds  raised  through  two  feet,  all  represent 
the  same  amount  of  work,  i.  e.,  ten  foot-pounds. 
TIME. 

The  interval  between  two  phenomena  or  changes  of 
condition.  The  unit  of  time  is  the  hour  and  its  sub- 
divisions. 

POWER—  HORSE  POWER. 

Power  is  the  rate  at  which  work  is  done,  and  is  there- 
fore equivalent  to  the  quantity  of  work  done  in  the 
unit  of  time,  expressed  in  foot-pounds,  kilogram- 
meters,  etc.,  per  hour,  minute  or  second.  The  unit 
commonly  employed  is  the  horse  power,  which  is  defined 
as  work  done  at  the  rate  of  550  foot-pounds  per  second, 
or  1,980,000  foot  pounds  per  hour. 
VELOCITY. 

The  length,  !,  of  path  traversed  by  a  moving  body  in 
the  unit  of  time,  t;  therefore— 


V  standing  for  velocity. 

MOMENTUM. 

Momentum  is  the  product  of  mass  (in  motion)  mul- 
tiplied by  its  velocity  or  force  multiplied  by  the  time 
during  which  it  acts. 


ENERGY.  9 

INERTIA. 

Inertia  expresses  the  inability  of  a  body  to  change 
its  condition  of  rest  or  motion,  unless  some  force  acts 
on  it. 

LAWS  OF  MOTION. 

Newton  propounded  the  following  laws  of  motion: 

1.  A  free  body  tends  to  continue  in  the  state  in 
which  it  exists  at  the  time,  either  at  rest  or  in  uniform 
rectilinear  motion. 

2.  All  change  of  motion  in  a  body  free  to  move  is 
proportional  to  the  force  applied,  and  it  is  in  the  direction 
of  that  force. 

3.  The  reaction  of  a  body  acted  upon  by  the  im- 
pressed force  is  equal,  and  directly  opposed  to,  that  force. 

STATICS. 

Statics  is  that  branch  of  science  which  treats  of  the 
relation  of  forces  in  any  system  where  no  motion  results 
from  such  action.  . 

DYNAMICS  OB  KINETICS. 

Dynamics  or  kinetics  treats  of  the  motion  produced 
in  ponderable  bodies  by  the  action  of  forces. 


CHAPTER  III.— ENEEGY.     . 

ENERGY. 

Energy  is  the  power  or  quality  for  doing  work.  We 
distinguish  between  different  forms  of  energy,  viz.: 

VISIBLE  ENERGY. 

This  is  the  energy  of  visible  motions  and  positions, 
and  is  subdivided  as  follows: 

KINETIC  ENERGY. 

Kinetic  or  actual  energy  is  energy  which  a  body 
possesses  by  virtue  of  its  motion,  such  as  the  energy  of 
winds,  ocean  currents,  etc. 

POTENTIAL  ENERGY. 

Potential  or  latent  energy  is  that  kind  of  energy 
which  a  body  possesses  by  virtue  of  its  position,  a  head 
of  water,  a  raised  weight,  a  coiled  spring,  etc. 

MOLECULAR  ENERGY. 

The  molecular  energy  comprises  the  energy  of  radi- 
ation or  radiated  matter,  i.  e,t  electricity,  light,  heat, 


10  MECHANICAL  REFRIGERATION. 

etc.;  molecular,  potential  energy  or  energy  of  chemical 
affinity,  etc. 

C.  G.   S.  UNIT  OF  ENERGY. 

The  unit  of  energy  is  one-half  of  the  energy  pos- 
sessed by  a  gramme  of  mass  when  moving  with  a  velocity 
of  one  centimeter  per  second.  This  unit  is  called  the 
erg.  The  erg  may  also  be  defined  as  the  work  accom- 
plished when  a  body  is  moved  through  a  distance  of  one 
centimeter  with  the  force  of  one  dyne,  that  is  a  "Dyne 
Centimeter." 
One  million  ergs  is  called  a  megerg. 

CONSERVATION  OF  ENERGY. 

The  total  amount  of  energy  in  the  universe,  or  in  any 
limited  system  which  neither  receives  nor  loses  any 
energy  to  outside  matter  is  invariable  and  constant. 

TRANSFORMATION  OF  ENERGY. 

The  different  forms  of  energy  are  convertible  or 
transformable  into  each  other,  so  that  when  one  form  of 
energy  disappears,  an  exact  equivalent  of  another  form 
or  kind  of  energy  always  makes  its  appearance.  (See 
"  Dissipation  of  Energy.") 

PHYSICS. 

Is  the  science  which  treats  of  the  transformations 
and  transference  of  energy,  broadly  speaking. 

SUBDIVISIONS  OF  PHYSICS. 

Physics,  therefore,  is  subdivided  into  a  science  of  op- 
tics or  radiation,  a  science  of  heat,  of  mechanics,  of 
electricity  and  of  chemistry.  Other  distinct  branches  of 
science  treat  on  the  specific  relations  between  two  kinds 
of  energies;  for  this  reason  we  speak  of  thermodynamics, 
electro-chemistry,  photochemistry,  thermochemistry, 
electro-dynamics,  etc. 

DISSIPATION  OF  ENERGY. 

In  our  efforts  to  transform  one  form  of  energy  into 
another,  a  certain  portion  of  the  first  energy  always  as- 
sumes a  lower  degree  of  tension;  it  is  dissipated  and  now 
represents  an  amount  of  energy  of  less  availability  for 
useful  purposes. 

ENERGY  OF  A  MOVING  BODY. 

The  amount  of  kinetic  energy  possessed  by  a  body  by 
virtue  of  its  motion  may  be  expressed  by  the  formula— 


in  which  E  stands  for  energy,  M  for  mass  and  v  for  velo- 
city. 


HEAT.  11 

MECHANISMS. 

A  machine  or  a  mechanism  is  a  contrirance  enabling 
us  to  transform  mechanical  energy,  by  changing  the 
direction,  power  and  velocity  of  available  forces  to  make 
them  serviceable  for  useful  proposes.  The  energy  sup- 
plied to  a  machine  is  partly  employed  to  do  the  useful 
work  required,  and  partly  it  is  consumed  in  doing  what  is 
called  internal  work,  by  overcoming  friction,  etc.  It  is 
the  lost  work  of  the  machine,  and  the  less  the  latter  the 
more  perfect  is  the  machine. 


CHAPTER  IV.— HEAT. 

HEAT. 

Heat  Is  a  form  of  energy,  and  represented  by  the 
kinetic  energy  of  the  molecules  of  a  body. 

SOURCES  OF  HEAT. 

As  sources  of  heat  we  may  quote:  Friction,  percus- 
sion and  pressure,  solar  radiation,  terrestrial  heat,  mo- 
lecular action,  change  of  condition,  electricity,  chemical 
combination,  more  especially  combustion. 

RADIANT  HEAT. 

The  foregoing  definition,  while  it  accounts  for  the 
phenomena  of  bodily  and  conducted  heat,  does  not  ac- 
count for  the  conditions  which  obtain  when  heat  passes 
from  one  body  to  a  distant  other  body  without  a  ponder- 
able intervening~medium,  or  without  perceptibly  heating 
the  intervening  medium,  i.  e.,  the  radiation  of  heat.  To 
explain  these  conditions  in  harmony  with  the  mechanical 
or  molecular  theory  of  physics,  it  is  supposed  that  the 
radiant  heat  is  in  the  nature  of  a  wave  motion  propa- 
gated .by  means  of  a  hypothetical  substance,  the  ether. 
ETHER. 

The  hypothetical  ether  which  is  the  supposed  vehicle 
for  the  transmission  of  the  supposed  wave  motion  consti- 
tuting radiant  energy  (radiant  heat  as  well  as  light),  in 
order  to  accomplish  such  transmission  in  accordance  with 
the  present  conceptions  of  these  phenomena  would  have 
to  possess  the  following  properties:  "Its  density  would 
have  to  be  such  that  a  volume  of  it  equal  to  about  twenty 
volumes  of  the  earth  would  weigh  one  pound;  its  pressure 


12  MECHANICAL  REFRIGERATION. 

per  square  mile  would  be  about  one  pound,  and  the  heat 
required  to  elevate  the  temperature  of  one  pound  for  1°  F 
would  have  to  be  equal  to  the  amount  of  heat  required  to 
raise  the  temperature  of  about  2,300,000,000  tons  of  water 
for  one  degree.  Such  a  medium  would  satisfy  the  require- 
ments of  nature  in  being  able  to  transmit  a  wave  of  light 
or  heat  180,000  miles  per  second,  and  to  transmit  some 
130  foot-pounds  of  heat  energy  from  the  sun  to  the  earth, 
each  second  per  square  foot  of  heat  normally  exposed, 
and  also  be  everywhere  practically  non-resisting  and 
sensibly  uniform  in  temperature,  density  and  elasticity." 
(Wood.) 

RADIANT  HEAT  AND  LIGHT. 

Kadiant  heat  follows  the  same  laws  regarding  re- 
fraction, reflection,  polarization,  etc.,  as  does  light. 

TEMPERATURE. 

The  temperature  of  a  body  is  proportional  to  the 
average  kinetic  energy  of  its  molecules,  and  is  measured 
by  the  thermometer. 

THERMOMETER. 

The  most  prevalent  form  of  thermometer  consists  of 
a  body  of  mercury,  enclosed  in  a  glass  tube  so  that  slight 
variations  of  expansion  due  to  change  of  temperature 
can  be  read  of  on  the  scale  attached.  Other  substances, 
like  alcohol,  air,  etc.,  are  also  used  as  thermometric  sub- 
stances instead  of  mercury. 

THERMOMETER  SCALES. 

Three  different  scales  are  in  use  for  thermometers, 
the  "Fahrenheit"  in  England  and  United  States,  the 
"Keaumur"  in  Germany  and  the  "Celsius"  or  "Centi- 
grade "  in  France,  and  for  scientific  and  technical  pur- 
poses, more  or  less,  all  over  the  world. 

The  scales  of  the  different  thermometers  compare  as 

follows:  Freezing-point  Boiling  point 

of  water.  of  water. 

Fahrenheit 32°  2^° 

Centigrade 0°  100^ 

Reaumur 

If  we  designate  the  scales  by  their  initials  the  follow- 
ing rules  apply  for  the  conversion  of  the  degrees  in  one 

another' 

C.=i(F.-32)=f  B. 

E.=|  (P.— 32)=|  C. 


HEAT. 
COMPARISON  OF  THERMOMETER  SCALES. 


13 


B. 

0. 

F. 

R. 

C. 

F. 

~"+80 

+100 

+212 

+23 

+28.75 

+83.75 

79 

98.75 

209.75 

22 

27.60 

81.50 

78  ' 

97.50 

207.50 

21 

26.25 

79.25 

77 

96.25 

205.26 

20 

25 

77 

76 

95 

203 

19 

23.75 

74.75 

75 

93.75 

200.75 

18 

22.50 

72.50 

74 

92.50 

198.50 

17 

21.25 

70.25 

73 

91.25 

196.25 

16 

20 

68 

72 

90 

194 

15 

18.75 

66.75 

71 

88.75 

191.75 

14 

17.50 

63.50 

70 

87.50 

189.50 

13 

16.25 

61.25 

69 

86.25 

187.25 

12 

15 

59 

68 

85 

185 

11 

13.75 

56.75 

67 

83.75 

182.75 

10 

12.50 

54.50 

66 

82.50 

180.50 

9 

11.25 

52.25 

66 

81.255 

178.25 

8 

10 

50 

64 

80 

176 

7 

8.75 

47.76 

63 

78.75 

173.75 

6 

7.50 

45.50 

62 

77.50 

171.50 

5 

6.26 

43.26 

61 

76.25 

169.25 

4 

5 

41 

60 

75 

167 

3 

3.75 

38.75 

59 

73.75 

164.75 

2 

2.50 

36.50 

58 

72.50 

162.50 

1 

1.25 

34.25 

57 
56 

71.25 
70 

160.25 
158 

-1 

0 
—1.25 

32 

29.75 

55 

68.75 

155.75 

2 

2.50 

27.50 

54 

67.50 

153.50 

3 

3.75 

25  25 

53 

66.25 

151.25 

4 

5 

23 

52 

65 

149 

5 

6.25 

20.75 

51 

63.75 

146.75 

6 

7.50 

18.50 

50 

62.50 

144.50 

7 

8.75 

16.25 

49 

61.25 

142.25 

8 

10 

14 

48 

60 

140 

9 

11.25 

11.75 

47 

58.75 

137.75 

10 

12.50 

9.50 

46 

57.50 

ia5.50 

11 

13.75 

7.25 

45 

56.25 

133.25 

12 

15 

5 

44 

55 

131 

13 

16.25 

2.75 

43 

53.75 

128.75 

14 

17.50 

0.50 

42 

52.50 

126.50 

15 

18.76 

—1.76 

41 

51.25 

124.25 

16 

20 

4 

40 

50 

122 

17 

21.25 

6.25 

39 

48.75 

119.75 

18 

22.50 

8.50 

38 

47.50 

117.50 

19 

23.75 

10.75 

37 

46.25 

115.25 

20 

25 

13 

36 

45 

113 

21 

26.25 

15.25 

35 

43.75 

110.75 

22 

27.50 

17.50 

34 

'42.50 

108.50 

23 

28.75 

19.75 

33 

41.25 

106.25 

24 

30 

23 

32 

40 

104 

25 

31.25 

24.25 

31 

38.75 

101.75 

26 

32.50 

26.50 

30 

37.50 

99.50 

27 

33.75 

28.76 

29 

36.25 

97.25 

28 

35 

31 

28 

35 

95 

29 

36.25 

33.25 

27 

33.75 

92.75 

30 

37.50 

26 

32.50 

90.50 

31 

38.75 

37!  75 

25 

31.25 

88.25 

32 

40 

40 

24 

30 

86 

MEASURING  HIGH  TEMPERATURES. 

Temperatures  which  are  beyond  the  reach  of  tlie 
mercurial  thermometers  (over  500°)  are  measured  by 
pyrometers  constructed  to  meet  the  wants  of  specific 
cases.  High  temperatures  may  be  estimated  approxi- 


14  MECHANICAL  REFRIGERATION. 

mateJy  by  heating  a  piece  of  iron  of  the  weight  w  up  to 
the  unknown  temperature  T,  and  then  immersing  the 
same  into  a  known  weight,  W,  of  water  of  the  tempera- 
ture t.  Then  if  t±  is  the  temperature  of  the  water  after 
immersion  and  s  the  specific  heat  of  the  iron  or  other 
metal,  T  is  found  after  the  formula: 


W  S 
ABSOLUTE  ZERO. 

The  zero  points  on  the  scales  of  thermometers  men- 
tioned are  arbitrarily  fixed,  since  the  expressions  of 
warm  and  cold  have  only  a  relative  significance.  The  real 
zero  point  of  temperature,  that  is,  that  point  at  which 
the  molecules  have  lost  all  motion,  the  energy  of  which 
represents  itself  as  heat,  is  supposed  to  be,  and  in  all  proba- 
bility is  over  460°  F.  below  the  zero  of  the  Fahrenheit 
thermometer.  At  that  temperature  there  is  an  entire  ab- 
sence of  heat  and  demonstrations  of  heat  phenomena, 
and  above  that  the  differences  in  temperatures  are  only 
such  of  degree,  but  not  in  kind.  Hence  the  impropriety 
of  speaking  of  heat  and  cold  as  such. 

If  t  is  a  given  temperature  in  degrees  Fahrenheit 
the  corresponding  degrees  T  expressed  in  absolute  tem- 
perature are  found  after  the  formula— 


UNIT  OF  HEAT. 

The  quantity  of  heat  contained  in  a  body  is  the  sum 
of  the  kinetic  energy  of  its  molecules.  Heat  is  meas- 
ured quantitatively  by  the  heat  unit,  which  also  varies  in 
different  parts  like  other  standards.  The  unit  used  in 
the  United  States  and  England  is  the  British  Thermal 
Unit  (abbreviated  B.T.U.)  and  represents  the  amount  of 
heat  required  to  raise  the  temperature  of  one  pound  of 
water  1°  F.  The  French  unit  is  the  calorie,  and  is  the 
quantity  of  heat  required  to  raise  the  temperature  of 
one  kilogram  of  water  from  0°  to  1°  Celsius. 

Some  writers  define  the  B.  T.  unit  as  the  heat  re- 
quired to  raise  the  temperature  of  one  pound  of  water 
from  32°  to  33°.  Others  make  this  temperature  from 
60°  to  61°,  and  still  others  define  it  as  that  amount  of 
heat  required  to  raise  rf  5  pound  of  water  from  the  freez- 
ing to  the  boiling  point.  The  two  last  definitions  give 
nearly  the  same  result,  and  may  be  considered  practically 
identical. 


HEAT. 


15 


C.  G.   S.   UNIT  OF  HEAT. 

We  have  no  unit  for  heat  corresponding  to  the  C.  G.  S. 
or  absolute  system.  The  small  French  calorie,  being  the 
heat  required  to  elevate  the  temperature  of  one  gram  of 
water  for  1°  Celsius  (from  17°  to  18°)  is  equivalent  to  41,- 
830,000  ergs. 

CAPACITY  FOR  HEAT. 

The  number  of  heat  units  required  to  raise  the  tem- 
perature of  a  body  for  one  degree  is  called  its  heat 
capacity.  It  gradually  increases  with  the  temperature. 

SPECIFIC  HEAT. 

The  ratio  of  the  capacity  for  heat  of  a  body  to  that 
of  an  equal  weight  of  water  is  specific  heat.  Hence  the 
figure  expressing  the  capacity  for  heat  of  one  pound  of  a 
body  in  B.  T.  U.  expresses  also  its  specific  heat,  and  vice 
versa. 

SPECIFIC  HEAT  OF    METALS. 


Antimony        • 

.0507 

Manganese  

.1441 

.0308 

Mercury    solid 

.0319 

.0939 

liquid... 

.0333 

0951 

Nickel 

.1086 

Cymbal  metal 

086 

PI  at  iiium,  sheet             .... 

.0324 

Gold                 

.0334 

"             SDOnfiTY 

.0329 

Iridium      •     •••      ••  

.1887 

Silver  

.0570 

.1298 

Steel 

.1165 

"      wrought          •  

.1138 

Tin              

.0569 

Lead  

.0314 

Zinc  

.0959 

SPECIFIC  HEAT  OF  OTHER  SUBSTANCES. 


STONES. 

Brickwork  and  masonry.. 
Marble    

.20 
.2129 
.2148 
.2169 
.2174 

.2411 
.2415 
.2031 
.2008 
.2017 

CARBONACEOUS—  Cont. 

.2019 
.197 

.1977 
.504 
.2503 
.2311 
.0872 
.1966 
.2026 

of  blast  furnaces 

SUNDRY. 
Place 

Quicklime  

Magnesian  limestone  
CARBONACEOUS. 

Coal          

Ice          .... 

Phosphorus  

Soda  

Sulphate  of  lead          

Cannel  coke           ...... 

"         of  lime  

Anthracite... 

SPECIFIC  HEAT  OF  LIQUIDS. 


.6588 

Turpentine  

.4160 

.3932 

Vinegar  

9200 

0333 

Water,  at  32°  F  .  .  .  . 

1  0000 

Olive  oil                  

.3096 

212°F  

1  0130 

Sulphuric  acid: 
Density    1  87 

3346 

32°  to  212°  F  
Wood  spirit     .  . 

1.0050 
6009 

«     '  '  i  30  

.6614 

Proof  spirit  

973 

16  MECHANICAL  REFRIGERATION. 

SPECIFIC  HEAT  OF  WATER  AT  VARIOUS  TEMPERATURES. 


Heat  to  Raise 

Heat  to  Raise 

Tempe- 
rature. 

Specific 
Heat. 

lib.  of  Water 
from  32°  F. 
to  Given 

Tempe- 
rature. 

Specific 
Heat. 

1  Ib.  of  Water 
from  32°  F. 
to  Given 

Temperature. 

Temperature. 

'Fahr. 

Units. 

°Fahr. 

Units. 

32 

1.0000 

0.000 

248 

1.0177 

217.449 

60 

1.0005 

18.004 

266 

1.0204 

235.791 

68 

1.0013 

36.018 

284 

1.0232 

254.187 

86 

1.0020 

54.047 

302 

1.0262 

272.628 

104 

1.0030 

72.090 

320 

1.0294 

291.132 

122 

1.0042 

90.157 

338 

1.0328 

309.690 

140 

1.0056 

108.247 

.     356 

1.0364 

328.320 

158 

1.0072 

126.378 

374 

1.0401 

347.004 

176 

1.0089 

144.508 

392 

1.0440 

365.760 

194 

1.0109 

162.  686 

410 

1.0481 

384.588 

212 

1.0130 

180.900 

428 

1.0524 

403.488 

230 

1.C153 

199.152 

446 

1.0568 

422.478 

USE  OF  SPECIFIC  HEAT. 

The  amount  of  heat  or  cold  necessary  to  elevate  or 
lower  the  temperature  of  w  pounds  of  a  body  having 
the  specific  heat  c  for  t  degrees  is  found  after  the  follow- 
ing equation:  8  =  c  X  t  X  w 

DETERMINATION  OF  SPECIFIC  HEAT. 

The  specific  heat  of  various  bodies  can  be  found 
from  the  table,  and  it  may  also  be  determined  experi- 
mentally as  follows  for  solid  substances  (to  find  the 
specific  heats  of  liquids  the  same  principle  is  followed,care 
being  taken  that  the  liquids  to  be  mixed  have  no  chemical 
affinity  for  each  other):  Take  a  known  weight,  w,  of  the 
substance  whose  specific  heat  is  to  be  determined,  and 
let  it  have  a  known  temperature,  t  (above  that  of  the 
atmosphere),  then  immerse  it  in  a  known  weight,  v,  of 
water  having  the  temperature  t'  and  now  observe  the 
temperature,  2,  acquired  by  the  mixture.  From  these 
quantities  the  specific  heat,  x,  of  the  substance  can  be  cal- 
culated after  the  formula  v  (z  —t'} 

X  =  ^(t^] 

If  the  substance  is  soluble  in  water  any  other  liquid 
whose  specific  heat  is  known  may  be  used  instead.  This 
method,  while  it  might  answer  for  rough  determinations, 
would  have  to  be  surrounded  by  special  safeguards  in 
order  to  allow  for  loss  by  radiation  of  the  vessel,  etc.,  in 
order  to  be  applicable  for  exact  determinations. 

TEMPERATURE  OF  MIXTURES. 

If  two  substances  having  respectively  the  weight  w 
tot,  the  temperatures  t  and  tlt  and  the  specific  heat  s 


HEAT.  17 

and  «!,  are  mixed  without  loss  or  gain  of  heat,  the  tem- 
perature, T,  of  the  mixture  is: 


W  S--Wi  S± 
EXPANSION  BY  HEAT. 

When  a  body  becomes  warmer  it  expands,when  it  be- 
comes cooler  it  contracts,  a  rule  of  which  ice,  however, 
is  one  of  the  exceptions. 

EXPANSION  OF  SOLIDS. 

Amount  of  linear  expansion  of  solids  may  be  com- 
puted by  the  following  formula  for  the  Fahrenheit  scale; 


(M-4) 


T180 

In  which  JDt  is  the  length  of  a  bar  at  any  temperature,  ft, 
knowing  its  length,  L,  at  any  other  temperature,  t,  and 
a  is  a  coefficient  to  be  obtained  from  the  following  table: 

COEFFICIENT  OF  EXPANSION  FROM  32°  TO  210°  F. 

Glass 0.000,861,30  Pine  wood  (length wise)... 0.000,3 

Platinum 0.000,884,20  Oak  wood 0.000,7 

Steel,  soft 0.001,078,80  Granite 0.000,8 

Iron,  cast 0.001,125,00  Limestone 0. 000,8 

Iron,  wrought 0.001,220,40  Antimony 0.001,1 

Steel,  hardened 0.001,239,50  Gold 0.001,4 

Copper 0.001,718,20  Ebonite 0.001,7 

Bronze 0.001,816,70  Nickel 0.0018 

Brass 0.001,878,20  Silver...  0.001.B 

Tin 0.002,173,00  Aluminum 0 .002,3 

Lead 0.002,857,50  Pine  wood  (crosswise) 0 . 005,8 

Zinc 0.002,941,70  Mercury  (in  glass  tube).  ..0.016,2 

EXPANSION  OF  LIQUIDS. 

The  expansion  of  liquids  by  heat  is  expressed  by  the 
volume  of  a  given  quantity  of  liquid  at  different  temper- 
atures, as  is  done  in  the  following  table  for  water,  show- 
ing also  that  at  the  point  of  maximum  density. 

The  maximum  density  of  water,  as  appears  from  this 
table,  is  between  32P  and  46°  F.;  above  46°  the  volume 
increases,  but  below  32°  it  increases  also.  Apparently 
this  is  an  exception  to  the  general  rule  that  all  bodies 
expand  by  heat  and  contract  when  the  temperature  is 
lowered.  This  exception,  however,  may  be  accounted 
for  when  we  assume  that  at  32°,  when  the  water  passes 
from  the  liquid  to  the  solid  state,  its  molecular  constitu- 
tion is  changed  also,  which  is  also  indicated  by  thf 
change  in  specific  heat  at  this  point. 


18 


MECHANICAL  REFRIGERATION. 


EXPANSION  AND  WEIGHT  OF  WATER  AT  VARIOUS 
TEMPERATURES. 


Tem- 
pera- 
ture. 

Relative 
Volume 
by  Ex- 
pansion. 

Weight 
of  One 
Cubic 
Foot. 

Weight 
of  One 
Imperial* 

Gallon. 

Tem- 
pera- 
ture. 

Relative 
Volume 
by  Ex- 
pansion. 

Weight 
of  One 
Cubic 
Foot. 

Weight 
of  One 
Imperial* 
Gallon. 

°Fahr. 

Pounds. 

Pounds. 

°Pahr. 

Pounds. 

Pounds. 

32 

1.00000 

62.418 

10.0101 

100 

1.00639 

62.022 

9.947 

35 

.99993 

62.422 

10.0103 

105 

1.00739 

61.960 

9.937 

f 

62.425 

] 

110 

1.00889 

61.868 

9.922 

39.1 

.  99989  <j 

maxi- 
mum 

\  10.  0112 

115 
120 

1.00389 
1.01139 

61.807 
61.715 

9.913 

9.897 

I 

dens'y 

J 

125 

1.01239 

61.654 

9.887 

40 

.99989 

62.425 

10.0112 

130 

1.01390 

61.563 

9.873 

45 

.99993 

62.422 

10.0103 

135 

1.01539 

61.472 

9.859 

46 

l.OOOOU 

62.418 

10.0101 

140 

1.01690 

61.381 

9.844 

50 

1.00015 

62.409 

10.0087 

145 

1.01839 

61.291 

9.829 

( 

62.400 

1 

150 

1.01989 

61.201 

9.815 

1 

ordi- 

155 

1.02164 

61.096 

9.799 

52.3 

1.  00029  ^ 

nary 

10.0072 

160 

1.02340 

60.991 

9.781 

I 

calcu- 

165 

1.02589 

60.843 

9.757 

! 

lations 

170 

1.02690 

60.7H3 

9.748 

55 

1.00038 

62.394 

10.0063 

176 

1.02906 

60.665 

9.728 

60 

1.00074 

62.372 

10.0053 

180 

1.03100 

60.548 

9.711 

62  1 

185 

1.03300 

60.430 

9.691 

mean 

190 

1.03500 

60.314 

9.672 

tem-^ 

1.00101 

62.355 

10.0000 

195 

1.03700 

60.198 

9.654 

pera- 

200 

1.03889 

60.081 

9.635 

ture  j 

205 

1.0414 

.59.93 

9.611 

65 

1.00119 

62.344 

9.9982 

210 

1.0434 

59.83 

9.594 

70 

1.00160 

62.313 

9.9933 

212 

.0466 

59.64 

9.665 

76 

1.00239 

62.275 

9.9871 

250 

.06243 

68.76 

9.422 

80 

1.00299 

62.232 

9.980 

300 

.09563 

56.97 

9.136 

85 

1.00379 

62.1*2 

9.973 

400 

.15056 

54.25 

8.703 

60 

1.00459 

62.133 

9.964 

500 

.22005 

51.16 

8.204 

95 

1.00554 

62.074 

9.955 

The  cubical  expansion,  or  expansion  of  volume,  of 
water,  from  32°  F.  to  212°  F.  and  upward,  is  given  in 
the  above.  The  rate  of  expansion  increases  with  the 
temperature.  The  expansion  for  the  range  of  tempera- 
ture from  32°  to  212°  is  .0466,  or  fully  41  per  cent  of  the 
volume  at  32°;  or  an  average  of  .000259  per  degree,  or  $£& 
part  of  the  volume  at  32P  F. 

EXPANSION  OF  LIQUIDS,  FROM  32°  TO  212°  F.— VOLUME 
AT  320=1. 


Liquid. 

Volume 
at  212°. 

Expan- 
sion. 

Liquid. 

Volume 
at  212°. 

Expan- 
sion. 

Alcohol  
Nitric  acid.  .  . 
Olive  oil  
Turpentine.. 

1.1100 
1.1100 

1.0800 
1.0700 

1-9 
1-9 
1-12 
1-14 

Sea  water  — 
Water  
Mercury  

1.0500 
1.0466 
1.018 

1-20 
1-22 
1-56 

TRANSFER  OF  HEAT. 

Heat  is  transferred  from  one  body  to  another  by  con- 
duction, radiation  and  convection. 

*0ne  imperial  gal.  Is  equal  to  1.203  wine  gale.  (U.  S.  standard). 


HEAT. 
INSULATORS. 


19 


Insulators  or  non-conductors  of  heat  are  of  special 
value  in  the  construction  of  ice  houses,  cold  storage 
rooms,  etc.,  and  the  following  table  shows  the  retentive 
power  of  various  substances,  together  with  the  percentage 
of  solid  matter  in  a  given  space  (in  first  column).  The 
figures  in  second  column  are  for  a  covering  one  inch  thick, 
and  a  difference  of  100°  F.  on  each  side  of  the  covering, 
and  at  temperatures  of  176°  F.  on  hot  side  of  covering, 
except  in  some  cases,  in  which  it  was  310°  F.,  as  stated. 


Non-conductors  One  Inch  Thick. 

Net 
Cubic  Inch  of 
Solid    Matter 
in  100. 

Heat  Units 
Transmitted 
per    sq.    Foot 
per   Hour. 

Still  air 

43 
108 
203 
36 
36 
44 
48 
41 
50 
50 
52 
56 
41 
45 
49 
60 
68 
78 

15 
£ 

75 

iS 

156 

50 

60 
52 
58 

78 

S 

80 
56 
99 
210 
131 
134 
296 
264 
335 
345 
290 
251 
197 
136 
129 
125 

"         "      —310° 

Wool—  310°    

43 

2.8 
2 
1 
5 
2 
2.1 
9.6 
8.5 
6.6 

Absorbent  cotton  . 

Raw  cotton  

Live  geese  feathers  =310°  .  . 

Cat-tail  seeds  and  hairs 

Scoured  hair,  not  felted  
Hair  felt  

Lampblack=310°  

Cork  charcoal—  3io°      

5.3 
11.9 
14.6 
7 
20.1 
31.3 
31.8 
16.2 
36.4 
30.4 
79.4 
5.7 
6 
2.3 
8.5 
13.6 
6 
8.8 
25.3 
3 
3.6 
8.1 
36.8 
30.6 
26.1 
52.9 

White  pine  charcoal  —  310° 

Rice  chaff  

Cypress  (Taxodium)  shavings. 

"                "         sawdust  

board.             

Yellow  poplar  (Liriodendron)  sawdust 

"                              "     cross-section 
"  Tunera  "  wood  board 

Slag  wool,  best    ...         .      .  . 

Carbonate  of  magnesium  

Calcined  magnesia  —310°.    .. 

"  Magnesia  covering,"  light  

heavv. 

Fossil  meal  —  310°  

Zinc  white  —  310°         

Ground  chalk  —  310° 

Asbestos  in  still  air 

"        "  movable  air. 

"  =310°  
Dry  plaster  of  Paris  =  310°  
Plumbago  in  still  air  
"  movable  air  =  310°  
Coarse  sand  =  3  10°  
Water                                       still 

Starch  jelly  very  firm 

Solution  sugar  70  per  cent, 

Castor  oil                                        

Cotton  seed  oil 

Lard  oil,                                         

20 


MECHANICAL   REFRIGERATION. 


CONDUCTION  OF  HEAT. 

The  flow  of  heat  from  a  warmer  to  a  colder  part  of  a 
body  is  called  conduction.  Some  bodies  conduct  heat 
much  more  rapidly  than  others,  hence  we  speak  of  good 
and  bad  conductors  of  heat.  Very  poor  conductors  and 
non-conductors  of  heat  are  also  called  insulators. 

RELATIVE  CONDUCTIVITY  OF  MATERIALS. 


Bismuth    0.011 

German  silver 0.109 

Iron 0.183 

Sandstone  (Neumann) 0.007 

Soft  coal  (Neumann) .0.0003 

Granite 0. 005 

Ice 0.006 

Marble... 


Gold 1.000 

Copper .    0.918 

Brass 0.150 

Zinc 0.305 

Silver 1.096 

Cadmium  0.221 

Tin 0.146 

Lead : 0.072 

INSULATION  OF  STEAM  PIPE. 

With  reference  to  the  insulation  of  steam  pipe,  Nor- 
ton estimates  the  loss  through  radiation  of  an  uncovered 
steam  pipe  carrying  steam  of  200  pounds  at  13.84  B.  T. 
U.  per  square  foot  per  minute.  Covering  the  pipe  as  in- 
dicated in  the  following  table,  the  radiation  is  reduced  to 
the  figures  given.  Box  A  is  a  %-inch  square  pine  box 
surrounding  the  pipe,  leaving  one  inch  minimum  space 
at  its  four  sides.  The  saving  is  calculated  on  above  basis. 


SPECIMEN. 

B.  T.  U.  per 

sq.  ft.  per  min. 
at  200  Ibs. 

Saving  on  one 
year  per  100 
sq.  ft.  pipe. 

Box  A- 
1    with  sand     

3.18 

134.60 

1  75 

39  40 

3*,  with  cork  and  infusorial  earth 
4   with  sawdust              .      ... 

1.90 
2  15 

38.90 
37.90 

6   with  charcoal  

2.00 

38.50 

2  46 

36.90 

Brick  wall  4  inches  thick      .. 

5  IB 

28  80 

Hair  felt  I  inch  thick          ...... 

2  61 

36.80 

Pine  wood,  1  inch  thick  
Spruce,  1  inch  thick  
Spruce,  2  inches  thick  

3.56 
3.40 
2.31 

38.80 
33.90 
37.50 

Spruce  3  inches  thick 

8.02 

38.50 

Oak  1  inch  thick 

3  65 

33.10 

Hard  pine  1  inch  thick  

3.72 

32.90 

NON-CONDUCTING  COATING  FOR  STEAM  PIPES. 

M.  Burnat's  experiments  were  made  with  cast  iron 
steam  pipes,  4.72  inches  in  diameter  externally,  M-inch 
thick,  in  a  large  unheated  hall  free  from  drafts.  They 
were  in  five  groups  differently  coated: 

First  Group. — Coated  with  straw  laid  lengthwise,  ,60 
inch  thick,  wrapped  with  straw  rope. 


HEAT.  21 

Second  Group. — Bare. 

Third  Group.— Each  pipe  laid  in  a  pottery  pipe,  in- 
closing an  air  space,  coated  with  a  mixture  of  loamy  earth 
and  chopped  straw,  covered  with  tresses  of  straw. 

Fourth  Group. —Co-died  with  cotton  waste,  one  inch 
thick,  wrapped  in  cloth  bound  with  cord. 

Fifth  Group.— Coated  with  a  plaster  of  clay  and  cow's 
hair,  2.36  inches  thick. 

The  results  are  given  in  the  following  table. 

CONDENSATION  OF  STEAM  IN  COATED  PIPES. 


Absolute 
Pressure 
01  Steam 

Temperatures. 

Steam  Condensed  per  Sq.  Foot  of 
External  Surface  of  Pipes  per  Hr. 

per 
Square 
Inch. 

Steam. 

Air. 

Differ- 
ence. 

Straw 
coat, 
Ibt. 

Bare 
2d. 

'Pottery 
coat, 
3d. 

Waste 
coat, 
4th. 

Plaster 
coat, 
5th. 

Lbs. 

QFahr. 

oFahrJoFuhr. 

Lb. 

Lb. 

Lb. 

Lb. 

Lb. 

16.5 

218.0 

46.4 

171.6 

.139 

.496 

.170 

.217 

.254 

16.5 

218.0 

33.8 

184.2 

.152 

.485 

.166 

.205 

.262 

•     18.4 

223.4 

33.7 

189.7 

.164 

.555 

.186 

.229 

.281 

18.4 

223.4 

27.1 

196.4 

.182 

.571 

.264 

.287 

.344 

22.0 

2;i3.2 

41.5 

191.7 

.246 

.576 

.258 

.244 

.320 

22.0 

233.2 

38.5' 

196.7 

.164 

.158 

.250 

22.0 

233.2 

36.1 

197.] 

.102 

".&l' 

.178 

.260 

22.0 

233.2 

28.9 

204.3 

.201 

.5P6 

.264 

.328 

".'346" 

25.7 

241.6 

43.3 

198.4 

.244 

.645 

.301 

.375 

.389 

25.7 

241.6 

3f5.5 

205.1 

.274 

.285 

.369 

2^.4 

249.1 

43.3 

205.8 

.252 

".121 

.270 

.342 

"!379 

29.4 

249.1 

30.6 

218.4 

.225 

.621 

.250 

.328 

.336 

Aver 

ages 

22.0 

233.1 

36.5 

196.6 

.581 

.229 

.286 

.324 

The  bare  pipe  was  afterward  coated  with  old  felt, 
which  had  been  treated  with  caoutchouc;  and  it  con- 
densed an  average  of  .313  pound  of  steam  per  square  foot 
per  hour. 

The  rates  of  condensation  and  of  emission  of  hea.t 
are  summarized  as  follows: 

SUMMARY  RESULTS. 


Coating-  of  Pipe. 

Steam  Condensed 
per  Square  Foot 
per  Hour. 

Heat  Emitted  per 
Square  Foot  per 
Hour. 

Total. 

Per  Jo  F. 
Difference 

Total. 

Per  lo  p. 
Difference 

Bare  pipe       

Pound. 
.531 

.200 
.229 
.2?6 
.313 
.321 
.307 

Pound. 

.00300 
.00102 
.00115 
.00146 
.00159 
.00165 
.00156 

Units. 

552.8 
190.3 
224.8 
272.1 
297.8 
308.3 
292.1 

Units 
2.812 
0.968 
1.108 
1.384 
1.515 
1.568 
1.486 

Straw 

Pottery  pipes  wii  h  air  space. 
Cotton  waste 

Felt  

Plaster                     .... 

The  same,  painted  white  

22  MECHANICAL  REFRIGERATION. 

RELATIVE  CONDUCTIVITIES  OF  METALS. 

Gold 1,000     Zinc .360 

Silver 973     Tin 304 

Copper 878     Lead 180 

Iron 374     Marble 25 

RADIATION  OF  HEAT. 

Heat  is  also  transmitted  from  one  body  to  another 
by  radiation.  In  this  case  the  temperature  of  the  inter- 
vening medium  remains  unaltered. 

THEORY  OF  HEAT  TRANSFERS. 

This  theory  asserts  that  all  bodies  are  constantly  giv- 
ing out  heat  by  radiation,  at  a  rate  depending  on  their 
substance  and  temperature,  but  independent  of  the  sub- 
stance and  temperature  of  the  bodies  surrounding  them; 
and  that  whether  a  body  remains  at  the  same  tempera- 
ture or  alters  its  temperature  depends  upon  whether  it 
receives  as  much  heat  from  other  bodies  as  it  yields  up 
to  them. 

ABSORPTION  OF  RADIANT  HEAT. 

When  heat  rays  fall  upon  a  body  a  portion  of  them 
is  reflected,  a  portion  of  them  transmitted,  and  the 
rest  of  them  is  absorbed  and  increases  the  temperature 
of  the  body,  lu  bodies,  therefore,  not  transparent  for 
heat  rays  the  reflected  and  absorbed  heat  complement 
each  other;  that  is  to  say,  a  good  reflector  is  a  bad  ab- 
sorber, and  vice  versa.  By  the  same  token,  bodies  which 
have  a  great  absorbing  power  have  also  a  great  emissive 
or  radiating  power,  but  are  bad  reflectors  for  heat,  and 
vice  versa.  Some  bodies,  however,  are  good  reflectors  for 
light,  and  at  the  same  time  excellent  absorbers  for  heat, 
like  white  lead,  for  instance. 

EMISSIVE  AND  ABSORBING  POWER  FOR  HEAT. 


Lampblack 100 

Whitelead 100 

White  paper 98 

Crown  glass 90 


Polished  silver 2.5 

Gold  leaf 4.3 

Copper  foil 4.9 

Polished  platinum 9.2 


The  following  table  has  evidently  been  compiled  on 
the  basis  that  the  radiating  and  reflecting  power  are 
strictly  complementary  to  each  other.  This  holds  good 
as  a  rule.  However,  it  is  one  that  is  not  without  excep- 
tions. Thus  white  lead  has  a  good  reflective,  but  also  a 
good  absorbing  power,  which  it  is  well  to  note. 


HEAT.  23 

COMPARATIVE  ABSORBING  OR  RADIATING  AND  REFLECT- 
ING PROPERTIES  OF  SOLIDS. 


Substance. 

Absorbing-  or 
Radiating 
Power. 

Reflecting 
Power. 

Brass,  bright  polished    ....  ........... 

Proportion, 
Per  Cent. 

7 

Proportion, 
Per  Cent. 
93 

11 

89 

7 

93 

Glass... 

90 

10 

Gold  

5 

95 

Ice  

85 

15 

25 

75 

Iron  wrought,  polished.           .....  ... 

23 

77 

Marble  

93  to  98 

7  to  2 

Mercury                             

23 

77 

Platinum,  polished  

24 

76 

Platinum  sheet 

17 

83 

Silver  leaf  on  glass*  

27 

73 

Silver   polished 

3 

97 

Steel,  polished 

17 

83 

Tin 

15 

85 

Water  

100 

o 

Writing  paper  

98 

a 

Zinc,  polished  

19 

81 

CONVECTION  OF  HEAT. 

Convection  of  heat  takes  place  when  heat  is  trans* 
ferred  from  one  place  to  another  by  the  bodily  moving  of 
th§  heated  substance,  as  it  takes  place  when  water  is 
heated  in  a  vessel,  the  hot  water  and  the  cold  constantly 
exchanging  places. 

COMPLICATED  TRANSFERS  OF  HEAT. 

The  phenomena  of  conduction,  radiation  and  con- 
vection are  complicated  and  combined  in  the  transmis- 
sion of  heat  through  metal  plates,  tubes,  jackets,  etc., 
and  the  quantitative  relations  may  be  derived  from  the 
following  data,  after  D.  K.  Clark's  tables,  etc.: 

The  heat  radiated  from  incandescent  coal  or  coke  is 
expressed  by  the  formula: 


E=  quantity  of  heat  radiated  per  square  foot  of  sur- 

face per  hour,  in  British  units. 
0  =  temperature  of  the  inclosure,  in  Fahrenheit  de- 

grees. 
t=  excess  temperature  of  surface  of  hot  body  above 

the  temperature  of  the  inclosure,  <9,  in  Fahren- 

heit degrees. 
a  =  constant,  1.00425. 

According  to  the  formula,  the  rate  of  radiation  in- 
creases in  a  much  more  rapid  ratio  than  the  excess  tern- 


24  MECHANICAL  REFRIGERATION. 

perature,  when  the  temperature  of  the  inclosure  ia  con- 
stant. 

The  heat  radiated  from  a  coal  or  a  coke  fire  is  esti- 
mated to  be  about  one-half  of  the  whole  heat  generated. 
It  increases  almost  as  fast  as  the  rate  of  combustion  of 
the  fuel  per  hour  per  square  foot. 

CONVECTION  OF  HEAT  FROM  AN  EXTERNAL  SURFACE. 
Surrounding  Medium. 

Air C=  .2849£  i-233 

Hydrogen. C=  .9827t 1  -233 

Carbonic  acid G  =  ,2759£ 1-233 

Olefiantgas C  —  .38m  l-m 

C=  quantity  of  heat,  in  British  units,  conveyed 
away  from  a  solid  body  by  a  gas  external  to  it, 
per  square  foot  of  surface  per  hour,  under  one 
atmosphere  of  pressure. 

t  =  excess  temperature  of  surface  in  Fahrenheit  de- 
grees. 

CONDENSATION  OF  STEAM   IN  BARE  PIPES  EXPOSED 
TO  AIR. 

Tredgold  found  that  steam  of  YI%  -pounds  absolute 
pressure  per  foot  was  condensed  in  cast  iron  pipes*in 
a  room  at  60°  F.,  at  the  rate  of  .352  pound  per  square  foot 
of  exposed  surface  per  hour;  or  .0022  pound  per  degree  of 
difference  of  temperature. 

The  following  results  were  found  by  M.  Clement. 
It  is  here  assumed  that  the  steam  was  of  20  pounds  abso- 
lute pressure  per  square  inch.  The  pipes  were  exposed 
in  a  room  at  77°  F. 

Bare  Surface.  Steam  Condensed  per 


Cast  iron  pipe,  horizontal 328  pound. 

""     "       ^  pit 
jipe,  J 
Blackened  pipe,  horizontal . . . 


Square  Foot  per  Hour. 

328 

Blackened  pipe,  horizontal 308 

Copper  pipe,  horizontal 267 

Blackened  pipe,  horizonl    ' 
Blackened  pipe,  upright. 

M.  Burnat  found  that  for  steam  of  22  Ibs.  absolute 
pressure,  with  196°. 6  F.  difference  of  temperature,  .581 
Ib.  was  condensed  per  square  foot  of  a  cast  iron  pipe, 
nearly  horizontal,  per  hour. 

Dr.  William  Anderson  experimented  with  a  tubular 
steam  heater,  of  2-inch  wrought  iron  tubes,  in  a  temper- 
ature of  59°  F.,  with  steam  of  51  Ibs.  total  pressure  per 
square  inch;  .785  Ib.  was  condensed  per  square  foot  per 
hour. 


HEAT. 


The  foregoing  results  are  collected  in  the  following 
tablet: 


Observer 

Temper- 
ature of 
Sur- 
round- 
ing Air. 

Differ- 
ence of 
Tempe- 
rature. 

Steam  Consumed 
per  Square  Foot 
per  Hour. 

Heat 

Emitted 
per  1°  F. 
Differ- 
ence of 
Tempe- 
rature. 

Total. 

Per  1°  F. 

Clement  

°Fahr. 
77 
60 
3«.5 
59 

°Fahr. 
151 
161 
196.6 
223 

Pound. 

.328 
.352 

.581 
.785 

Pound. 

.00217 
.0022 
.0030 
.0035 

Units. 
2.07 
2.10 

2.81 
3.22 

Tredgold  

Burnat 

Anderson  

From  these  data  the  following  approximate  formulae 
are  deduced: 

Condensation  of  steam  in  cast  iron  pipes,  in  air,  per 
square  foot  of  surf  ace  per  hour  at  ordinary  temperatures: 


t* 
''  55000 


—  .12 


Heat  emitted  from  cast  iron  pipes,  in  air,  per  square  foot 
of  surface  per  hour,  at  ordinary  temperatures: 


fe=ir-114 


Heat  emitted  from  cast  iron  pipes,  in  air,  per  square  foot 
/>/  surface  per  degree  of  difference  of  temperature  of  steam  and 
air,  per  hour,  at  ordinary  temperatures. 

, ,      t  114 

=  ~58~      ~T 

s  =  quantity  of  steam  condensed  in  pounds. 

ji  =  quantity  of  heat  emitted  in  units. 

h'=  quantity  of  heat  emitted,  per  degree  of  difference 

of  temperature. 
i=difference  of  temperature,  in  Fahrenheit  degrees. 

The  latent  heat  of  steam  of  22  pounds  total  pressure 
per  square  inch,  950  units  per  pound,  is  employed  as  the 
heat  factor,  as  an  average  value. 

The  following  table  has  been  calculated  by  means  of 
these  formulae: 


MECHANICAL  REFRIGERATION. 


STEAM  CONDENSED  IN  BARE  CAST  IRON  PIPES  IN  AIR, 

AND    HEAT    EMITTED,    AT    ORDINARY 

TEMPERATURES. 


Steam. 

Differ- 
ence or 
Excess 
of  Tem- 
perature 
of  Steam 
above 
62°  Fahr. 

Steam  Condensed 
per  Square  Foot 
per  Hour. 

Heat  Emitted. 
per  Square  Foot 
per  Hour. 

Total 
Pressure 
per 
Square 
Inch. 

Tempe- 
rature. 

Total. 

Per 
1°  F.  of 
Differ- 
ence. 

Total. 

Per 
1°  F.  of 
Differ- 
ence. 

Pounds. 

14.7 
18 
21.5 
26 
31 
36.5 
43 
51 

0  Fahr. 
212 
222 
S32 
242 
252 
262 
272 
282 

0  Fahr. 

150 
160 
170 
180 
190 
200 
210 
220 

Pounds. 
29 
346 
.405 

.47 
.54 
.607 
.682 
.76 

Pounds. 
.00193 
.00216 
.00238 
.00261 
.00284 
.00303 
.00325 
.00345 

Units. 
276 
329 
384 
446 
513 
577 
648 
722 

Units. 
1.84 
2.05 
2.26 
2.48 
2.70 
2.89 
3.08 
3.28 

For  the  increased  rate  of  condensation  induced  by  a 
draft  of  air,  compared  with  that  caused  in  the  still  air 
of  a  room,  a  bare  steam  boiler,  in  open  air,  was  tested. 
Steam  of  50  Ibs.  absolute  pressure  per  square  inch  was 
condensed  at  the  rate  of  1.25  pounds  per  square  foot  of 
external  surface  per  hour;  or,  for  a  difference  of  236°  of 
temperature,  .0053  pound  per  degree  of  difference;  show- 
ing that  4.79  units  of  heat  per  degree  was  emitted,  or  a 
half  more  than  from  a  pipe  in  still  air. 

EXPERIMENTS  NEEDED. 

The  foregoing  and  following  data  relate  nearly  all  to 
the  emission  of  heat  from  pipes,  etc.,  filled  with  water 
or  steam.  It  would  of  course  be  also  highly  desirable  to 
have  similar  data  for  ammonia,  especially  for  anhydrous 
ammonia,  at  the  temperatures  of  condenser,  freezing 
tank,  brine  tank  and  cold  storage  rooms.  But  such  ex- 
periments have  not  been  made  so  far.  Numerical  data 
on  this  topic  have  been  abstracted  from  practical  experi- 
ence, and  such  as  were  attainable  in  this  way  have  been 
mentioned  in  their  place  in  the  second  part  of  this  book, 
but  are  necessarily  somewhat  arbitrary. 

COOLING  OP  WATER  IN  PIPES  EXPOSED  TO  AIR. 

Mr.  Wm.  Anderson  experimented  with  2-inch  wrought 
iron  pipes,  ^  inch  thick,  galvanized,  and  4-inch  cast  iron 
pipes,  iV  mck  thick,  through  which  hot  water  was  passed. 


HEAT.  27 

Results  are  given  in  the  following  table.    The  ultimate 
results  harmonize  with  those  for  the  use  of  steam  in 

pipes.      . 

COOLING  OF  WATER  IN  PIPES  EXPOSED  TO  AIR. 


Two-inch  Wrought 
Iron  Pipes. 

Four-inch  Cast  Iron 
Pipes. 

Number  of  exper-  > 
iment        ) 

1 

53° 

103°.7 

233.7 
2.25 

2 

53° 

49°.  4 

104.4 
c2.11 

3 

52°.5 

25°  .4 

46.45 
1.83 

4 
52° 

14°.3 

19.7 

1.39 

1 
60° 

62°.3 

99.5 
1.59 

2 
60° 

45°.8 

69.9 
1.53 

3 

60° 

33°.9 

49.5 
1.46 

4 

59° 

27°  .3 

38.2 
1.40 

Temperature    o  f 
the  atmosphere 
Fahr    

Average  differ- 
ence of  temper- 
aturesof  the  wa- 
ter and  the  air 
Fahr  

Total  heat   emit-' 
ted  per  square 
foot   per   hour. 
Units         

Heat  emitted  per' 
1°  P.  difference 
of  temperature 

Units... 

Tredgold  experimented  with  small  vessels  of  different 
materials,  in  which  water  was  cooled  from  a  temperature 
of  180°  to  one  of  159°,  in  a  room  at  58P.  The  heat  emitted 
per  square  foot  per  hour  per  degree  of  mean  difference  of 
temperature  was  as  follows: 

Tin  plate 1.37  units. 

Sheetiron 2.24      tt 

Glass 2.18      - 

Also,  in  a  2^-inch  cast  iron  pipe,  %  inch  thick,  water 
was  cooled  from  152°  to  140°  F.,  in  a  room  at  67°.  The 
heat  emitted  per  square  foot  per  hour  per  degree  of  dif- 
ference of  temperature  was  as  follows: 

Ordinary  rusty  surface 1.823  units. 

Black,  varnished 1.900     " 

White  (two  coats  of  lead  paint) 1. 778 

TRANSMISSION  OF  HEAT  THROUGH  METAL  PLATES  FROM 
WATER  TO  WATER. 

In  a  metal  tubular  refrigerator,  hot  wort  was  cooled 
by  water  at  such  a  rate  that,  taking  averages,  80  units  of 
heat  passed  from  the  wort,  and  was  absorbed  by  the 
water  per  square  foot  of  cooling  surface  per  1°  F.  dif- 
ference of  temperature.  The  water  and  the  wort  were 
moved  in  opposite  directions. 

M.  P4clet  proved  experimentally  that  the  rate  of 
transmission  of  heat  was  directly  as  the  difference  of 
temperature  at  the  two  faces  of  metal  plates. 


28 


MECHANICAL  REFRIGERATION. 


TRANSMISSION  OF  HEAT  THROUGH  METAL  PLATES  FROM 
STEAM  TO  WATER. 

The  rate  of  transmission  of  heat  from  steam  through 
a  metal  plate  to  water  at  the  other  side  is  practically 
uniform  per  degree  of  difference  of  temperature.  The 
following  table  gives  average  results  of  performance,  from 
which  it  appears  that  the  transmission  is  much  more 
effective  for  evaporating  than  for  heating  water,  twice  as 
much  for  flat  copper  plate,  three  times  as  much  for  copper 
pipe,  one-fourth  more  for  cast  iron  plate.  Also,  that  pipe 
surface  is  one-fifth  more  effective  than  flat  plate  surface 
for  heating,  and  more  than  twice  as  much  for  evapora- 
tion—the result  of  better  circulation,  no  doubt. 

HEATING  AND  EVAPORATING  WATER  BY  STEAM  THROUGH 
METALS. 


Metal  Surface. 

Per  Square  Foot  per  1°  F.  Difference  of 
Temperature. 

Steam  Condensed. 

Heat  Transmitted. 

Heating. 

Evaporat- 
ing. 

Heating. 

Evaporat- 
ing. 

Copper  plate  
Copper  pipe 

Pounds. 

.248 
.291 
.077 

Pounds. 
.483 
1.070 
.105. 

Units. 
276 
312 

82 

Units. 
534 
1034 
100 

Mr.  Isherwood  experimented  with  cylindrical  metal 
pots,  10  inches  in  diameter,  21^  inches  deep;  %  inch, 
34  inch  and  %  inch  thick;  turned  and  bored.  They  were 
placed  in  a  steam  bath  of  from  220°  to  320°  F.  Water  at 
212°  was  supplied  to  the  pots,  and  evaporated.  The  rate 
of  evaporation  per  degree  of  difference  of  temperature 
was  the  same  for  all  temperatures;  and  the  rate  was  the 
same  for  the  different  thicknesses.  The  respective  weights 
of  water,  and  heats  consumed  per  square  foot  of  inside 
surface  per  degree  of  difference  were  as  follows: 


Copper 

Brass 

Wrought  iron 

Cast  iron 


Water  at  212*. 
.665  Ib. 

.577  " 
.387  " 
.327  "  - 


Heat. 

642.5  units 
556. 8     " 

373.6  " 

315.7  " 


The  differences  of  results  for  the  same  metal  evi- 
dently arise  in  part  from  the  comparative  activity  of  cir- 
culation, and  in  part  from  the  condition  and  position  of 
the  heating  surfaces. 


HEAT.  29 

CONDENSATION  OF  STEAM  IN  PIPES  OR  TUBES  BY  WATER 
EXTERNALLY. 

From  the  results  of  experiments  with  surface  con- 
densers, in  which  the  steam  was  passed  through  the 
tubes,  it  appears  that  500  units  of  heat  by  condensation 
were  transmitted  per  square  foot  of  tube  surface  per  hour 
per  1°  F.  difference  of  temperature.  The  condensers 
were  arranged  in  three  groups  of  tubes  successively  trav- 
ersed by  the  condensing  water.  In  another  case,  where 
the  condenser  was  arranged  in  two  groups,  from  220  to 
240  units  were  transmitted. 

Mr.  B.  G.  Nichol  experimented  with  an  ordinary  sur- 
face condenser  brass  tube,  %  inch  in  diameter  outside, 
No.  18  wire  gauge  in  thickness ;  encased  in  a  3%-inch 
iron  pipe.  Steam  of  32^  pounds  total  pressure  per 
square  inch  occupied  the  interspace,  while  cold  water  at 
58°  F.  initial  temperature  was  run  through  the  brass 
tube.  Three  experiments  were  made  with  the  tubes  in 
a  vertical  position,  and  three  in  a  horizontal  position. 

Vertical  Position.  Horizontal  Position. 

1,  2,  3,  4,  5,  6, 

Velocity  of  water  through  tube,  in  feet  per  minute, 
81,  278,  390,  78,  307,  415  feet. 

Steam  condensed  per  square  foot  of  surface  per  hour, 
for  1G  F.  difference  of  temperature, 

.335,      .436,       .457,  .480,         .603,        609  pound. 

Heat  absorbed  by  the  water,  per  square  foot  per  hour, 
per  1°  F.  difference  of  temperature, 

346,        449,        466,  479,        621,        699  units. 

The  rate  of  condensation  was  greater  in  the  hori- 
zontal position  than  in  the  vertical  position.  Also,  the 
efficiency  of  the  condensing  surface  was  increased  by  an 
increase  of  velocity  of  the  water  through  the  tube,  nearly 
in  the  ratio  of  the  fourth  root  of  the  velocity  for  vertical 
tubes;  and  nearly  as  the  4. 5  root  for  horizontal  tubes, 

TRANSMISSION    OF    HEAT    THROUGH   METAL  PLATES    OR 
TUBES,  FROM  AIR  OR  OTHER  DRY  GAS  TO  WATER. 

The  rate  of  transmission  of  con vected  heat  is  prob- 
ably from  2  to  5  units  of  heat  per  hour  per  square  foot  of 
surface  per  1°F.  of  difference  of  temperature. 

In  a  locomotive  fire  box,  where  radiant  heat  co-oper- 
ated with  con  vected  heat,  the  following  results  have  been 


30  MECHANICAL  REFRIGERATION. 

obtained  in  generating  steam  of  80  pounds  pressure  per 
square  inch.  The  temperature  of  the  fire  is  taken  at 
2,000°  F. 

Heat  Transmitted 

Water  Evaporated  per  Square  Foot  per 
per  Square  Foot    Hour  perl0  F.Differ- 
per  Hour.       ence  of  Temperature. 

Burning  coke,  75  pounds  ) 

per  square  foot  of  [     25%  pounds.     14^  units. 

grate ) 

Burningbriquettes,  ) 

74^    pounds    per  [     35  20 

square  foot  of  grate  ) 

There  are  in  practice  little  or  no  differences  between 
iron,  copper  and  lead  in  evaporative  activity,  when  the 
surfaces  are  dimmed  or  coated,  as  under  ordinary  condi- 
tions. 

COMPARATIVE  RATE  OF  EMISSION  OF  HEAT  FROM  STEAM 
PIPES  IN  AIR  AND  IN  WATER. 

It  appears  that  for  equal  total  difference  of  tempera- 
ture, the  rate  of  emission  of  heat  from  steam  pipes  in 
water  amounts,  in  round  numbers,  to  from  150  to  250 
times  the  rate  in  air,  according  as  the  pipes  are  vertical 
or  horizontal. 

COMPARATIVE  RATE  OF  EMISSION  OF  HEAT  FROM  WATER 
TUBES  IN  AIR  AND  IN  WATER  AT  REST  AND  IN  MOTION. 

It  appears  that  the  rate  of  emission  from  water- 
tubes  in  water  was  about  twenty  times  the  rate  in  air. 
Mr.  Craddock  proved  it  experimentally  to  be  twenty-five 
times.  When  the  water  tube  was  moved  through  the 
air  at  a  speed  of  fifty-nine  feet  per  second,  it  was  cooled 
in  one-twelfth  of  the  time  occupied  in  still  air.  In  water, 
moved  at  a  speed  of  three  feet  per  second,  the  water  in 
the  tube  was  cooled  in  half  the  time. 

PASSAGE  OF  HEAT  THROUGH  METAL  PARTITIONS. 

From  eome  recent  observations  made  in  Germany 
the  following  table,  giving  the  transmission  of  heat 
through  metal  partitions  per  hour,  per  square  foot  and 
per  one  degree  F.  difference  between  each  side,  viz.: 

Smoke  or  air  through  metal  to  air 1.20  to      1.70B.  T.  U. 

Steam  through  metal  to  air 2. 40  to      8.40 

Water  through  metal  to  air  or  reverse 2.15  to      3. 15 

Steam  through  metal  to  water :  200.00  to  240.00 

Steam  through  metal  to  hoiling  water 1,000.00  to  1,200.00 

Water  through  metal  to  water 72. 00  to     W.OO 

LATENT  HEAT. 

When  a  body  passes  from  the  solid  to  the  liquid 
state,  or  from  the  liquid  to  the  gaseous  or  vapor  state,  a 


HEAT. 


31 


certain  amount  of  heat  is  required  to  bring  about  the 
change.  As  this  heat  is  absorbed  during  the  process  of 
fusion  or  vaporization  it  is  called  latent  heat  of  fusion 
and  latent  heat  of  evaporation  (latent  heat  contained  in 
the  vapor). 

LATENT  HEAT  OF  FUSION. 

The  heat  which  becomes  latent  during  the  fusion  or 
melting  of  a  body  is  used  or  absorbed  while  doing  the 
work  of  disintegrating  the  molecular  structure,  doing 
internal  work  as  it  is  called. 

TABLE  SHOWING  LATENT  HEAT  OF  FUSION. 


Thermal 
units. 

Ice 142.5 

Nitrate  of  ammonia 113.2 

Nitrate  of  soda 104.1 

Phosphate  of  potash 85.1 

Nitrate  of  potash 78.4 

Chloride  of  calcium 64.3 

Zinc 60.6 

Platinum 48. 8 

Silver 37.8 


Thermal 
units. 

Tin 25.5 

Cadmium 24.5 

Bismuth 22.7 

Sulphur 16.8 

Lead 9.6 

Phosphorus 9.0 

D'Arcet's  alloy 6.1 

Mercury 0.1 


MELTING  POINTS,  ETC. 


°Fahr. 

°Fahr. 

Aluminum  -| 

Full 
red 
heat 
1150 
507 
1690 
1996 
2156 
2282 
2012 
—108 
32 
45 
112 
109  to 
120 

Iron,  cast,  white  •} 

1992  to 
2012 
2912 
617 
—39 
1873 
2372  to 
2562 
442 
773 
120 
239 
92 
14 
142 
154 

"    wrought  .  .  . 

Lead  

Bismuth  ....... 

Mercury 

Silver  

Copper.........  

Cfppl 

"       pure. 

Tin 

Iron,  cast,  gray  

Zinc           

Ice           

Sulphur  ... 

Tallow  

Phosphorus  

Turpentine 

Wax,  rough  
"       bleached  

EFFECT  OF  PRESSURE  ON  MELTING  POINT. 

•  Substances  which  expand  during  solidification,  like 
water,  have  their  freezing  points  lowered  by  pressure, 
and  those  which  contract  in  solidification  have  their 
freezing  points  raised  by  pressure. 

LATENT  HEAT  OF  SOLUTION". 

When  a  body  is  dissolved  in  water  or  in  any  other 
liquid,  or  if  two  solid  bodies  (salt  and  snow,  for  an  ex- 
ample) mix  to  form  a  liquid,  a  certain  amount  of  heat 
becomes  likewise  latent;  it  is  called  the  latent  heat  of 
fusion.  Since  the  latent  heat  of  fusion  in  the  case  of 


32  MECHANICAL  REFRIGERATION. 

such  mixtures  is  taken  from  the  mixture  itself,  the  tem- 
perature falls  correspondingly,  as  shown  by  the  table 
on  frigoriflc  mixtures. 

For  practical  purposes  the  mixtures  of  snow  and 
hydrochloric  acid,  or,  where  acid  is  objectionable,  the 
mixture  of  snow  and  potash,  is  very  serviceable  to  pro- 
duce refrigeration  on  a  small  scale.  The  mixture  of 
sodium  sulphate,  ammonium  nitrate  and  nitric  acid  is 
also  recommendable. 

LIST  OF  FRIGORIFIC  MIXTURES. 

Thermometer  Sinks 
Degrees  F. 


Ammonium  chloride. 

Potassium  nitrate „ 

Water 16       "     ) 


i  chloride 5  parts  ) 

Potassium  nitrate 5       "     >•  From  +  50°  to  +  10° 


Ammonium  chloride 5  parts "! 

Potassium  nitrate 5       "     1    „ 

Sodium  sulphate 8       "     f  From  +  80°  to  +  4 

Water 16       "     J 

Sodium  nitrate 3  parts  I   „ 

Nitric  acid,  diluted 2       "     f  From  +  50°  to  -  3 

Ammonium  nitrate 1  part  ) 

Sodium  carbonate. 1  >  From  -f  60°  to  —  7° 

Water 1  ) 

Sodium  phosphate 9  parts  I    „ 

Nitric  acid,  diluted 4       "     f   From +  50°  to -12° 

Sodium  sulphate 5  parts  I   ,, 

Sulphuric  acid,  diluted 4       "     f  From  +  50   *°  + 

Sodium  sulphate 6  parts  1 


Ammonium  chloride 4  L  ».*..  _i  «U  *-,      10° 

Potassium  nitrate 2       "     f  From  4- 50   to  -  1 

Nitric  acid,  diluted 4       '    j 

Sodium  sulphate 6  parts  ) 

Ammonium  nitrate ...  5  V  From  +  50°  to  —  40 

Nitric  acid,  diluted 4  ) 

Snow  or  pounded  ice 2  parts  I  -0 

Sodium  chloride 1       "     J 

Snowor  pounded  ice 5  parts 


Sodium  chloride. 

Ammonium  chloride 1 

Snow  or  pounded  ice 24  parts 

Sodium  chloride 10 

Ammonium  chloride 5 

Potassium  nitrate 6 

Snow  or  pounded  ice 12  parts 

Sodium  chloride 6 

Ammonium  nitrate 5 

3 


to-l*° 


to -18° 


to- 25 


cXum  chloride::::::'::::::::::::::  5 pa«ts}  From+32-  to-4o° 

Ca?cTum'cmorideVcryVtailized. .'.'.'.'.'.'  3  ,    «  S  \  From +  32°  to  — 5C° 


HEAT,  M 

HEAT  BY   CHEMICAL  COMBINATION. 

As  one  of  the  chipf  sources  of  heat  chemical  combina- 
tion has  been  mentioned,  which  may  be  defined  as  the 
process  which  takes  place  when  the  ultimate  constituent 
parts  (atoms)  of  one  or  more  elementary  bodies  unite  with 
those  of  another  elementary  body  or  bodies  to  form  a 
substance  essentially  different  in  its  properties  from  those 
of  the  original  bodies. 

ELEMENTARY    BODIES. 

Substances  which  cannot  be  resolved  into  two  or 
more  different  substances  are  called  elementary  bodies, 
elements  or  simple  bodies. 

CHEMICAL   ATOMS. 

Chemically  considered,  an  atom  is  the  smallest  parti- 
cle of  matter  entering  into  or  existing  in  combinations. 
The  atomic  weight  is  a  number  expressing  the  ratio  of 
the  weight  of  the  atoms  of  an  element  to  the  weight  of  an 
atom  of  hydrogen,  the  latter  being  taken  as  unit. 

MOLECULES. 

The  smallest  quantity  of  an  elementary  body,  as  well 
as  of  a  compound  body,  which  is  capable  of  having  an 
independent  existence  is  called  a  molecule.  A  molecule, 
therefore,  is  a  combination  of  several  atoms  of  one  and 
the  same  or  of  different  elements. 

CHEMICAL  SYMBOLS. 

The  chemical  elements  are  expressed  by  symbols 
which  are  the  initial  letters  of  their  Latin  or  English 
name.  The  symbols  also  represent  the  relative  quan- 
tity of  one  atom  of  an  element. 

The  composition  of  the  molecule  of  a  body  is  indi- 
cated by  the  symbols  of  its  constituents.  The  num- 
ber of  atoms  of  each  element  present  is  denoted  by  a 
number  placed  at  the  lower  right  hand  end  of  the  sym- 
bol. Thus  H2  represents  a  molecule  of  hydrogen  which  is 
composed  of  two  atoms,  and  H2O  represents  a  molecule 
of  water,  which  is  composed  of  two  atoms  of  hydrogen  and 
one  of  oxygen.  The  atomic  weight  of  hydrogen  being  1 
and  that  of  oxygen  16,  it  is  readily  seen  how  the  formula 
II 2 O  yields  the  percentage  composition  by  a  simple  cal- 
culation. 

ATOMICITY. 

Atomicity  or  valence  is  that  property  of  an  element 
by  virtue  of  which  it  can  hold  in  combination  a  definite 


34 


MECHANICAL  REFRIGERATION. 


number  of  other  atoms,  the  atomicity  of  an  elementary 
body  is  measured  by  the  number  of  atoms  of  hyurogen 
which  can  be  held  in  combination  by  an  atom  of  the  ele- 
mentary body  in  question,  the  atomicity  of  hydrogen 
being  taken  as  unit.  Thus  by  referring  to  the  following 
table  it  is  readily  seen  how  one  atom  of  chlorine  will 
hold  in  combination  one  atom  of  hydrogen,  one  atom  of 
oxygen  two  atoms  of  hydrogen,  one  atom  of  nitrogen 
three  atoms  of  hydrogen,  and  one  atom  of  carbon  four 
atoms  of  hydrogen  and  form  saturated  compounds. 

For  obvious   reasons  the  rare  and  new  elements, 
argon,  helium,  atherion,  etc.,  are  not  mentioned. 

TABLE  OF  PROPERTIES  OF  ELEMENTS. 


Element. 

Sym- 
bol. 

Atom- 
icity. 

Atomic 
Weight. 

Specific 
Gravity. 

Al 

IV 

27  *i 

2KO 

Antimony  

Sb 

v 

122 

6  7 

Arsenic 

As 

v 

7K 

BrtK 

Barium  

Ba 

II 

137 

4  0 

Bismuth            . 

Bi 

y 

OAQ 

8  75 

Boron  .      ... 

B 

III 

Jl 

2  68 

Bromine 

Br 

I 

80 

2  Q« 

Cadmium        ..                     .... 

Cd 

II 

112 

1  58 

Calcium 

Ca 

II 

40 

1  65 

Carbon   

c 

IV 

12 

2  33 

Chlorine  

Cl 

I 

35  5 

Cr 

VI 

52  5 

6  5 

Cobalt 

Co 

VI 

58  8 

Cu 

II 

63  5 

8  958 

Fluorine. 

F 

I 

19 

Gold 

Au 

in 

IQfi  7 

19  26 

H 

I 

1 

Iodine               . 

I 

in 

127 

4  948 

Iridium       ...         

Ir 

VI 

198 

21  15 

Iron 

Fe 

VI 

56 

7  79 

Lead. 

Pb 

IV 

207 

11  36 

Lithium     

Li 

i 

7 

594 

Mg 

ii 

24 

1  70 

Manganese  

Mn 

VI 

55 

8  03 

Mercury 

Hff 

II 

200 

13  go 

Nickel             

Ni 

VI 

58  8 

Nitrogen            

N 

Y 

14 

Oxygen      

o 

II 

16 

Palladium  . 

Pd 

IV 

106  5 

11  40 

Phosphorus  

p 

v 

31 

1  g40 

Platinum  

Pt 

IV 

197  4 

21  15 

K 

I 

39 

865 

Rhodium.  ...           .         

Rh 

VI 

104 

12  1 

Selenium 

Se 

VI 

79 

4  28 

Silicon  

Si 

IV 

28  5 

2  49 

Silver. 

Air 

I 

108 

10  53 

Sodium  

Na 

I 

23 

9722 

Strontium               

Sr 

11 

87  5 

2  543 

g 

Vf 

32 

2  07 

Tellurium            

Te 

VI 

128 

6  180 

Tin  

Sn 

IV 

118 

Titanium.          ..           

Ti 

IV 

50 

W 

VI 

184 

Uranium      .... 

Ur 

VI 

12i) 

18.4 

Vanadium 

v 

v 

51  2 

5  5 

Zinc... 

Zn 

II 

65 

7.13 

HEAT.  36 

GENERATION  OF  HEAT. 

The  generation  of  heat  by  chemical  combination  is 
explained  by  the  fact  that  the  resulting  compounds  pos- 
sess less  energy  than  the  constituent  elements  before 
they  unite  or  combine.  The  difference  of  energy  before 
and  after  combination  appears  in  the  form  of  heat,  elec- 
tricity, etc.  By  the  same  token  heat  is  absorbed  during 
the  decomposition  of  chemical  compounds. 

MEASURE  OF  AFFINITY. 

The  amount  of  heat  or  other  form  of  energy  devel- 
oped during  a  chemical  change  is  a  measure  for  the 
chemical  work  done  or  the  amount  of  affinity  displayed 
during  the  change. 

TOTAL  HEAT  DEVELOPED. 

The  total  amount  of  heat  or  energy  developed  dur- 
ing a  chemical  change  depends  solely  upon  the  initial  and 
final  condition  of  the  participating  bodies  (the  initial  or 
final  condition  of  the  system),  and  not  on  any  intermedi- 
ate conditions.  In  other  words,  the  heat  developed  dur- 
ing a  chemical  change  is  the  same  whether  the  change 
takes  place  in  one  operation  or  in  two  or  more  separate 
processes. 

MAXIMUM  PRINCIPLE. 

Of  all  chemical  change  which  may  take  place  within 
a  system  of  bodies,  without  the  interference  of  outside 
energy,  that  change  will  take  place  which  causes  the 
greatest  development  of  heat,  as  a  general  rule. 

According  to  the  more  modern  conceptions  it  is  held 
that  that  change  will  take  place  which  will  cause  the 
greatest  dissipation  of  energy,  or  by  which  the  entropy  of 
the  system  will  suffer  the  greatest  increase,  or  by  which 
the  greatest  amount  of  energy  will  be  dissipated.  (For 
definitions  of  entropy  see  Chapters  VII  and  VIII.) 

EXPRESSIONS  FOR  HEAT  DEVELOPED. 

The  amount  of  heat,  expressed  in  units,  developed  or 
absorbed  during  a  chemical  process  may  be  conveniently 
used  in  connection  with  the  chemical  symbols.  Thus  the 
formula 

P6  +  2/=P6/2-h  7.1400  U 

signifies  that  207  parts  of  lead  combine  with  254  parts  of 
iodine  to  form  461  parts  of  iodide  of  lead,  and  develop 
thereby  7.1400  units  of 


36  MECHANICAL  REFRIGERATION. 

HEAT  OF  COMBINATION  OF   SUBSTANCES   WITH   OXYGEN. 


Substances. 

Product. 

Units  of  Heat  Evolved. 

By  1  Ib.  of 
Substance. 

By  1  Ib.  of 
Oxygen. 

By    1  Atom 
of  Substance 
in  Pounds. 

Hydrogen  
Wood  charcoal  
Sulphate,  native  .  .  . 
Phosphorus(yellow) 
Zinc  

H2O 
ct>2 
SO2 

P205 

Zn.  0 
F30? 
CuO 
CO, 
CuO 

60,986 
14,220 
3,996 
10,345 
2,394 
2,848 
1,085 
4,325 
561 

7,623 
5,332 

3,996 
8,017 
9,703 
7,475 
4,309 

60,986 
170,640 
127,872 
320,683 
156,610 
159,466 
68,947 
121,111 
32,947 

Iron 

Carbonic  oxide  
Cuprous  oxide  

COMBUSTION. 

Combustion  is  the  rapid  combination  of  combustible 
material  (fuel)  with  oxygen. 

SPONTANEOUS  COMBUSTION. 

In  order  to  start  the  combustion  of  a  combustible 
body  it  is  generally  necessary  to  elevate  its  temperature 
or  to  bring  it  in  contact  with  a  burning  body.  In  other 
words,  it  must  be  ignited.  If  a  body  undergoes  com- 
bustion without  ignition  it  is  a  case  of  spontaneous 
combustion  ;  and  if  combustion  takes  place  without  the 
appearance  of  a  flame  or  light  it  is  called  slow  combustion. 

INFLAMMABLE  BODIES. 

Bodies  which  are  able  to  undergo  combustion  as  with 
the  appearance  of  a  flame  are  called  inflammable. 

EXPLOSIVE  BODIES. 

If  combustion  of  a  body  takes  place  at  once  or  sim- 
ultaneously throughout  its  whole  mass,  an  explosion 
generally  takes  place,  especially  if  the  body  is  confined 
in  a  limited  space  and  if  the  products  of  the  combustion 
are  of  a  gaseous  nature.  Therefore  such  bodies  are 
called  explosives. 

AIR  REQUIRED  IN  COMBUSTION. 

The  volume  of  air  consumed  chemically  in  the  com- 
bustion of  fuel  is  expressed  by  the  formula: 


—  .40) 

A  =  volume  of  air  as  at  62°  F.,  and  under  one  atmos- 
phere of  pressure,  in  cubic  feet  per  pound  of  fuel 
A'—  weight  of  air  as  at  62°  F.  per  pound  of  fuel. 
(7  =  percentage  of  constituent  carbon. 
H  =  percentage  of  constituent  hydrogen. 
O  =»  percentage  of  constituent  oxygen. 


HEAT.  37 

The  weight  of  the  air  thus  found  by  volume  is  equal 
to  the  volume  divided  by  13.14.  Or  it  is  found  directly 
by  the  formula: 

^'=.116(C+3If—  .40) 

In  these  formulae  the  heat  evolved  by  the  combus- 
tion of  the  sulphur  constituent  is  not  noticed,  as  it  is 
trifling  in  proportion. 

GASEOUS  PRODUCTS. 

The  volume  of  the  volatile  or  gaseous  products  of  the 
complete  combustion  of  one  pound  of  a  fuel,  as  at  62°  F., 
at  atmospheric  pressure,  is,  by  formula: 

V=  1.52  (7+  5.52S" 

The  weight  of  the  gaseous  products  is,  by  formula: 
w  =  .1260+.  358  H 

y=  volume  of  gaseous  products,  in  cubic  feet. 
tc  ==  weight  of  gaseous  products,  in  pounds. 
C  =-  percentage  of  constituent  carbon. 
H=  percentage  of  constituent  hydrogen. 

The  volume  at  any  other  temperature  is  found  by  tfce 
formula  for  expansion  of  gases,  given  elsewhere. 

The  proportion  of  free  or  unconsumed  air  usual  y 
present  in  the  gaseous  products  is  determined  by  mum- 
plying  the  percentage  of  oxygen  ,  found  by  analysis,  by  4.35. 
The  product  is  the  percentage  of  free  air  in  parts  of  t/  « 
whole  mixture. 

HEAT  GENERATED. 

The  heat  generated  by  combustion  is  as  follows: 

Carbon  .......................  14,500  heat  units  per  pound 

Hydrogen  ......................  62,000 

S  ulphur  ..............  ;  .........  4,000 

The  heating  power  of  fuels  containing  carbon  ar>d 
hydrogen  is  approximately  expressed  by  the  formula: 

h  =  145  (C  +  4.28H) 
in  which  h  is  the  total  heat  of  combustion. 

The  evaporative  efficiency  for  one  pound  of  fuel  is  - 
e  =  .15(O+4.29.ff) 


e  =  weight  of  water  evaporable  from  and  at  21  2P,  Jn 
pounds,  per  pound  of  fuel. 

The  maximum  temperature  of  combustion  of  carbon 
is  about  5,000°  F.  ;  and  that  of  hydrogen  is  about  5,800°  JP. 


38 


MECHANICAL  REFRIGERATION. 
HEAT  OF  COMBUSTION  OF  FUELS. 


Fuel. 

Air  Chemically 
Consumed  per 
Pound  of  Fuel. 

Total 
Heat  of 
Combus- 
tion of 
One 
Pound  of 
Fuel. 

Equivalent 
Svaporative 
Power,  from 
and  at  212° 
F.,  Water 
per  Pound 
of  Fuel. 

Coal  of  average  compo-  1 
sit/ion 

Pounds. 

10.7 

10.81 
8.85 
11.85 
6.09 

4.57 

9.51 
7.52 
5.24 

9.9 

4.26 
14.33 
17.93 

Cub.  Ft. 
at  62°  F. 

140 

142 
116 
156 

80 

60 

125 
99 
69 

130 

56 

188 
235 

Units. 

14,700 

13,548 
13,108 
17,040 
10,974 

7,951 

13,006 
12,279 
8,260 

12,325 

8,144 
20,411 
27,531 

Pounds. 

15.22 

14.02 
13.57 
17.64 
11.36 

8.20 
13.46 
12.71 
9.53 

12.76 

8.43 
21.13 
28.50 

Coke         

Lignite 

Asphalte 

Wood  desiccated 

Wood,  25  per  cent 
ture          

mois-  1 

Wood    charcoal, 
cated 

desic-  1 

Peat,  desiccated. 

Peat,  30  per  cent 

mois-  ) 

Peat     charcoal, 

desic-  1 

Straw                 .     . 

• 

Petroleum  oils  — 

Coal  gras,  per  cubic  foot  | 

630 

.70 

at  62U  F  

j 

COAL. 

Coal  consists  mainly  of  carbon,  which  varies  from  50 
per  cent  to  80  per  cent,  by  weight,  of  the  fuel.  Lignite  or 
brown  coal  contains  from  56  to  76  per  cent  of  carbon.  The 
average  composition  of  coal  is,  say,  80  per  cent  of  carbon, 
5  per  cent  of  hydrogen,  1%  per  cent  of  sulphur,  1£  per 
cent  of  nitrogen,  8  per  cent  of  oxygen,  and  4  per  cent  of 
ash.  The  fixed  carbon  or  coke  averages 61  percent.  The 
average  specific  gravity  is  1.279:  average  weight  of  a  solid 
cubic  foot,  80  pounds;  and  of  a  cubic  foot  heaped,  50 
pounds;  average  bulk  of  one  ton  heaped,  44%  cubic  feet; 
equivalent  evaporative  efficiency,  15.40  pounds  of  water 
per  pound  of  coal,  from  and  at  212°  F. 

Bituminous  coals  hold  from  6  per  cent  to  10  per  cent 
of  water  hygroscopically;  Welsh  coals  from  %  per  cent 
to  2M  per  cent. 

COKE. 

Coke  contains  from  85  to  97%  per  cent  of  carbon; 
from  M  to  2  per  cent  of  sulphur,  and  from  1%  to  14%  per 
cent  of  ash.  The  average  composition  may  be  taken  as 
93%  per  cent  of  carbon,  1^  per  cent  of  sulphur,  5%  per 
cent  of  ash.  It  weighs  from  40  pounds  to  50  pounds  per 
cubic  foot  solid,  and  about  30  pounds  broken  and  heaped. 
The  volume  of  one  ton  heaped  is  from  70  to  80  cubic 


HEAT.  ^  39 

feet;  average,  75  cubic  feet.  Coke  is  capable  of  absorb- 
ing from  15  to  20  per  cent  of  moisture.  There  is  or- 
dinarily from  5  per  cent  to  10  per  cent  of  hygrometric 
moisture  in  coke. 

LIGNITE. 

Lignite  or  brown  coal  consists  chiefly  of  carbon,  oxy- 
gen and  nitrogen;  averaging  in  perfect  lignite,  69  per 
cent  of  carbon,  5  per  cent  of  hydrogen,  20  per  cent  of 
oxygen  and  nitrogen,  and  6  per  cent  of  ash.  The  weight 
is  about  80  pounds  per  cubic  foot.  Imperfect  lignite 
weighs  about  72  pounds  per  cubic  foot. 

CHIMNEY  AND  GRATE. 

The  quantity  of  good  coal,  C,in  pounds,  that  may  be 
consumed  per  hour  with  a  chimney  having  the  height, 
If,  above  the  grate  bars,  a  sectional  area,  A,  in  square 
feet  at  the  top,  may  be  expressed  by  the  formula— 

C=16  A  VI? 
and  the  total  area  of  flre  grate  G  in  square  feet — 


1071 
HEAT  BY  MECHANICAL  MEANS. 

Mechanical  work  is  also  a  source  of  heat,  and  in 
nearly  all  cases  where  work  is  expended,  the  appearance 
of  an  equivalent  amount  of  heat  is  observed..  The  heat 
due  to  friction,  percussion,  etc.,  is  an  example  of  this 
kind,  as  also  is  the  heat  generated  by  the  compression 
of  gases  and  vapors  (see  Thermodynamics). 

The  height  of  chimney  for  a  given  total  grate  area, 
the  diameter  at  the  top  being  equal  to  one-thirtieth  of 
the  height,  is 


The  side  of  a  square  chimney  equal  in  sectional  area 
to  a  given  round  chimney  is  equal  to  the  product  of  the 
diameter  by  0.886;  the  equivalent  fraction  of  the  height 
for  the  side  of  a  square  chimney  is  one-thirty-fourth. 

Conversely,  the  diameter  of  a  round  chimney  equal 
in  sectional  area  to  a  given  square  chimney  is  equal  to 
the  product  of  the  side  of  the  square  by  1.13. 

When  the  top  diameter  of  the  chimney  is  one-thir- 
tieth of  the  height— a  good  proportion— the  quantity  of 
coal  that  may  be  consumed  per  hour  is  expressed  by  the 
formula— 


40  MECHANICAL  REFRIGERATION, 

CHAPTER  V.—  FLUIDS;  GASES;  VAPORS. 

FLUIDS  IN  GENERAL. 

Fluids  may  be  generally  defined  as  bodies  whose 
molecules  are  displaced  by  the  slightest  force,  which 
property  is  also  called  fluidity,  and  it  is  possessed  in  a 
much  larger  degree  by  gases  than  by  liquids. 

Gases  are  eminently  compressible  and  expansible, 
while  liquids  are  so  but  in  a  slight  degree. 

VISCOSITY. 

The  property  of  liquid  to  drag  adjacent  particles 
a  ong  with  it  is  called  viscosity  (Internal  Friction). 

PASCAL'S  LAW. 

Pressure  exerted  anywhere  upon  a  liquid  is  trans- 
» itted  undiminished  in  all  directions  and  acts  with  the 
same  force  on  all  equal  surfaces  in  a  direction  at  right 
angles  to  those  surfaces. 

BUOYANCY  OF  LIQUIDS. 

The  pressure  which  the  upper  layer  of  a  liquid  exerts 
on  the  lower  layers,  is  consequently  also  exerted  in  an 
upward  direction,  causing  what  is  termed  the  buoyancy 
ol!  liquids.  It  is  on  account  of  the  buoyancy  of  liquids 
tlhat  a  body  weighed  under  liquid  loses  a  part  of  its 
\reight,  equal  to  the  weight  of  the  displaced  liquid 
( Archimedian  principle). 

SPECIFIC  GRAVITY  DETERMINATION. 

By  ascertaining  the  loss  in  weight  of  a  body  immersed 
under  water  its  volume  may  be  readily  ascertained,  it  being 
equal  to  the  volume  of  water  corresponding  to  the  lost 
weight.  This  principle  is  used  to  determine  the  specific 
gravities  of  bodies  in  various  ways;  for  instance,  for  solid 
bodies,  by  dividing  their  weight  in  air  by  the  loss  of 
weight  which  they  sustain  when  weighed  under  water. 

HYDROMETERS. 

From  among  the  instruments  frequently  used  to 
ascertain  the  specific  gravity  of  liquids,  and  by  inference 
their  strength,  we  mention  those  called  hydrometers  as 
based  on  the  Archimedian  principle.  They  are  generally 
made  of  a  weighted  body  (usually  of  glass),  having  a 
thinner  stem  at  the  upper  end  provided  with  a  scale  di- 
vided in  degrees.  The  degrees  may  be  arbitrary  or  show 
specific  gravities  or  the  strength  of  some  particular  liquid 


FLUIDS;  GASES;  VAPOliS. 


41 


or  solution  in  per  cents;  in  the  latter  case  the  instru- 
ment is  called  Saccharometer,  Salometer,  Alcoholometer, 
Acidometer,  Alkalimeter,  etc.,  according  to  the  liquid  it 
is  designed  to  test.  Hydrometers  for  different  liquids  or 
purposes,  provided  they  cover  the  same  range  of  specific 
gravities,  may  be  used  for  either  liquid  when  the  relation 
their  degrees  bear  to  each  other  is  known.  For  some  of 
the  more  current  hydrometers,  these  relations  are  shown 
in  the  following  table : 


TABLE  SHOWING   SPECIFIC  GRAVITY  CORRESPONDING  TO 

DEGREES,  TWADDLE,   BEAUME  AND  BECK,  FOR 

LIQUIDS  HEAVIER  THAN  WATER. 


'1-1 
Q)  ® 

Corresponding  Sp.  Gr. 

It 

Corresponding  Sp.  Gr. 

sl 

3Q 

Twaddle 

Beau  me. 

Beck. 

if 

3Q 

Twaddle 

Bcaume. 

Beck. 

0 

1.000 

1.000 

1.000 

21 

1.105 

L1M 

.1409 

1 

1.005 

1.007 

1,0059 

22 

1.110 

1.176 

.1486 

2 

1.010 

1.014 

1.0119 

23 

1.115 

1.185 

.1565 

3 

1.015 

1.020 

1.0180 

24 

1.120 

1.195 

.1644 

4 

1.020 

1.028 

1.0241 

25 

1.125 

1205 

.1724 

5 

1.025 

1.034 

1.0303 

26 

1.130 

1.215 

.1806 

6 

1.030 

1.041 

1.0366 

27 

1.135 

1.225 

.1888 

7 

1.035 

1.049 

1.0429 

28 

1.140 

1.236 

.1972 

8 

1.040 

1.057 

1.0194 

29 

1.145 

1245 

.2057 

9 

1.045 

1064 

1.0559 

30 

1.150 

1.256 

1.2143 

10 

1.050 

1.072 

1.0325 

32 

1.160 

1.278 

1.2319 

11 

1.055 

i.o;o 

1.0692 

34 

1.170 

1.300 

1.2500 

12 

l.OfO 

1.088 

1.0759 

36 

1.180 

1.324 

1.2380 

13 

1.065 

1.096 

1.0828 

88 

1.190 

1.349 

1.2879 

14 

1.070 

1.104 

1.0897 

40 

1.200 

1.375 

.3077 

15 

1.075 

1.113 

1.0068 

45 

1.225 

1.442 

.3600 

16 

1.080 

1.121 

1.1039 

50 

1.250 

1.515 

1.4167 

17 

1.085 

1.130 

l.llll 

55 

1.275 

1.596 

.4783 

18 

1.090 

1.138 

1.1184 

60 

1.300 

1.690 

5454 

19 

1.095 

1.147 

1.1258 

65 

1.325 

1.793 

.6190 

20 

1.100 

1.157 

1.1333 

7U 

1.350 

1.909 

1.7000 

There  Is  a  slight  difference  between  the  indications  of  the 
Reaume  scale  in  different  countries.  The  manufacturing  chem- 
ists of  the  United  States  have  adopted  the  following  formula  for 
converting  the  Beaume  degrees  into  specific  gravity: 


Specific  gravity^ 


which  gives  specific  weight  slightly  higher  than  those  in  the  fore- 
going table.    (See  also  table  in  Appendix.) 

PRESSURE  OF  LIQUIDS. 

The  pressure  exerted  by  a  column  of  liquid  at  its 
bottom  or  base  is  proportional  to  the  vertical  height  of 
the  column  of  liquid,  its  specific  gravity  and  to  the  area 
of  the  bottom,  and  independent  of  the  shape  or  thickness 
pf  the  column  of  liquid. 


42  MECHANICAL  REFRIGERATION. 

WATER  PRESSURE. 

The  pressure  in  pounds,  P,  of  a  column  of  water  h 
feet  high  is— 

P  s=  .4335  h  per  square  inch, 
and  P  as  62.425  h  per  square  foot. 

SURFACE  TENSION  OF  LIQUIDS. 

The  layer  of  a  liquid  which  separates  the  same  from 
a  gas  or  vacuum  has  a  greater  cohesion  than  any  other 
layer  of  the  liquid,  owing  to  the  fact  that  the  attraction 
exerted  on  this  layer  by  the  interior  of  the  liquid  is  not 
counteracted  by  any  attraction  on  the  outside.  The  sur- 
face is,  as  it  were,  stretched  over  by  an  elastic  skin 
which  exerts  a  pressure  on  the  interior, which  pressure 
is  termed  surface  tension.  It  increases  with  the  co- 
hesion of  the  liquid. 

VELOCITY  OF  FLOW  OF  LIQUIDS. 

The  velocity  with  which  a  liquid  flows  through  an 
opening  depends  only  on  the  height  of  the  liquid  above 
the  orifice  and  is  independent  of  the  density  of  the  liquid. 
The  velocity,  v,  in  feet  per  second  is  expressed  by  the  for- 
mula—   

V=    V  2  g  h    =8  V  h 

g  being  the  acceleration  per  second  due  to  gravity,  and  h 
the  depth  of  the  orifice  below  the  surface,  both  expressed 
in  feet. 

QUANTITY  OF  FLOW. 

The  quantity  of  a  liquid,  say  water,  discharged 
through  an  opening  depends  on  the  area  of  the  opening, 
A  (in  square  feet),  and  also  on  the  shape,  etc.,  of  the  ori- 
fice. If  the  orifice  is  a  hole  in  the  thin  wall  of  a  vessel, 
the  quantity,  E  (in  cubic  feet),  discharged  is  expressed  by 


A  short  cylindrical  appendix  to  the  opening  woulc" 
increase  the  discharge  to— 

E  —  6.56  A  */2h.- 

and  an  appendix  haying  the  best  form  of  a  conic  frus- 
trum  will  nearly  discharge  the  theoretical  amount 

E  —  8  A  V  h 


FLUIDS;  GASES;  VAPORS.  43 

FLOW  OF  WATER  IN  PIPES. 

The  mean  velocity,  v,  of  water  in  a  cast  iron  pipe  of 
the  length,  Z,  and  the  diameter,  d,  under  the  head,  h,  is— 


v  = 


The  velocity  is  affected  by  the  surface  of  pipe,  and 
the  viscosity  or  interior  friction  of  the  liquid  (hydraulic 
friction). 

QUANTITY  OF  FLOW  THROUGH  PIPES. 

Dawning's  formula  for  the  quantity,  E,  in  cubic  feet 
of  water  discharged  by  channel  or  pipe  under  the  head, 
/i,  in  feet  is  as  follows: 


E  =  100  a  t/ 


I  being  the  length  of  pipe  in  feet;   a,  sectional  area  of 
current  in  square  feet;  c,  wetted  perimeter  in  feet. 

D  =  —  1-~  =  hydraulic  mean  depth. 

HEAD  OF  WATER 

The  head,  h,  approximately  required  to  move  water 
with  a  velocity  of  180  feet  per  minute  through  a  clean  cast 
iron  pipe,  having  a  diameter  D  inches  and  the  length 
I  in  feet,  is  — 


WATER  POWER. 

The  theoretical  effect  of  water  power  expressed  in 
foot-pounds  per  minute,  is  equal  to  the  weight  of  the 
water  falling  per  minute,  multiplied  by  the  height 
through  which  the  water  falls.  Divided  by  33,000,  it 
expresses  horse  powers.  The  practical  effect  depends 
on  the  efficiency  of  the  motor  (water  wheel,  turbine, 
engine,  etc.).  The  power  required  to  lift  water  is  calcu- 
lated in  the  same  manner. 

HYDROSTATICS  AND  DYNAMICS. 

The  science  which  treats  of  the  condition  of  liquids 
while  at  rest  is  called  hydrostatics,  and  that  which  treats 
of  the  motion  of  liquids  is  called  hydrodynamics. 


44  MECHANICAL  REFRIGERATION. 

CONSTITUTION  OF  GASES. 

In  a  general  way  the  term  gas  has  been  defined  in  the 
foregoing.  Speaking  more  specifically,  a  gas  is  a  body  in 
which  the  distance  between  the  constituent  atoms  or 
molecules  is  so  great  that  the  dimensions  of  the  mole- 
cules themselves  may  be  neglected  in  comparison  there- 
with. The  atoms  or  molecules  in  a  gas  are  constantly 
vibrating  to  and  fro,  and  the  average  momentum  or 
energy  of  this  motion  represents  the  temperature  of  the 
gas.  The  vehemence  or  force  with  which  the  atoms  or 
molecules  impinge  on  the  walls  of  a  surrounding  vessel 
in  consequence  of  this  motion  represents  the  pressure  of 
the  gas. 

PRESSURE  AND  TEMPERATURE. 

In  accordance  with  the  foregoing  definition  the 
pressure,  volume  and  temperature  of  a  gas  are  in  direct 
connection,  which  is  expressed  by  the  laws  of  Boyle  and 
St.  Charles. 

BOYLE'S  LAW. 

The  law  of  Boyle  or  of  Mariotte  asserts  that  the  vol- 
ume of  a  body  of  a  perfect  gas  is  inversely  proportional 
to  its  pressure,  density  or  elastic  force,  if  its  temperature 
remains  the  same. 

ST.  CHARLES  LAW. 

If  a  gaseous  body  is  heated  while  the  pressure  re- 
mains constant,  its  volume  increases  proportionally 
with  the  temperature.  The  increase  of  volume  for  every 
degree  F.  is  equal  to  ^3  of  its  volume  at  32°  F. 

UNIT  OF  PRESSURE. 

The  general  unit  of  pressure  is  the  pressure  of  the 
atmosphere  per  square  inch,  which  is  equal  to  that  of  a 
column  of  water  of  about  thirty  feet,  or  that  of  a  col- 
umn of  mercury  of  about  thirty  inches,  and  also  equiva- 
lent to  a  pressure  of  14.7  pounds — in  round  numbers  fif- 
teen pounds  per  square  inch. 

ABSOLUTE  AND  GAUGE  PRESSURE. 

The  pressure  gauges  in  general- use  indicate  pressure 
in  pounds  above  the  atmospheric  pressure;  it  is  called 
gauge  pressure.  To  convert  gauge  pressure  into  abso- 
lute pressure  14.7  has  to  be  added  to  the  former. 

Smaller  pressures  are  designated  by  the  number  of 
inches  of  mercury  which  they  will  sustain,  or,  after  the 


FLtTIDS;  GASES;   VAPORS. 


45 


F  ranch  system,  by  millimeters  of  mercury,  which  are 
compared  in  the  following  table  for  ordinary  pressures  of 
the  surrounding  atmosphere. 

COMPARISON   OF  THE  BRITISH  AND  METRICAL 
BAROMETERS. 


Inches. 

Millimeters. 

Inches. 

Millimeters. 

Inches. 

Millimeters. 

27.00 

685.788 

38.40 

721.347 

29.80 

756.906 

27.10 

688.338 

38.50 

733.887 

29.90 

759.446 

27.20 

690.867 

28.60. 

736.437 

30.00 

761.986 

27.30 

693.407 

38.70 

738.967 

30.10 

764.536 

27.40 

695.947 

28.80 

731.507 

30.20 

767.066 

87.50 

698.487 

28.90 

734.047 

30.30 

769.606 

87.60 

701,037 

39.00 

736.587 

30.40 

773.146 

17.70 

703.567 

39.10 

739.127 

30.50 

774.686 

•27.80 

706.107 

29.20 

741.667 

30.60 

777.226 

87.90 

708.647 

39.30 

744.306 

30.70 

779.  766 

88.00 

711.187 

29.40 

746.746 

30.80 

782.306 

28.10 

713.737 

29.50 

749.286 

30.90 

784.846 

28.30 

716.267 

29.60 

751.836 

88.30 

718.807 

29.70 

754.366 

ACTION   OF  VACUUM. 

The  pressure  of  the  atmosphere  is  the  cause  of  the 
raising  of  water  by  suction  pumps,  the  air  in  the  pumps 
being  removed  by  the  movement  of  the  piston,  and  its 
space  occupied  by  water  forced  up  by  the  pressure  of  the 
outside  atmosphere.  For  the  same  reason  such  a  pump 
cannot  lift  water  higher  than  thirty-two  feet,  a  column 
of  water  of  this  height  exerting  nearly  the  same  pressure 
as  the  atmosphere  at  the  earth's  surface.  For  the  same 
reason  the  mercury  in  a  barometer  (or  glass  tube  from 
-which  the  air  is  withdrawn)  stands  about  twenty-nine 
inches  high,  vary  ing  with  the  pressureof  the  atmosphere, 
between  twenty-seven  and  thirty  inches  at  the  earth's 
surface,  but  decreases  with  the  height  above  the  earth 
at  the  rate  of  0.1  inch  for  84  feet. 

MANOMETERS— GAUGES. 

The  instruments  for  measuring  higher  gaseous  press- 
ures are  usually  called  manometers  or  gauges. 

WEIGHT  OF  GASES. 

The  weight  of  gases  is  determined  by  weighing  a 
glass  balloon  filled  with  the  same,  and  by  subtracting 
from  this  weight  that  of  balloon  after  the  same  has  been 
evacuated  by  means  of  an  air  pump.  One  hundred  cubic 
inches  of  air  weighs  31  grains  at  a  pressure  of  the  atmos- 
phere of  30  inches,  and  at  a  temperature  of  60°  F.;  there- 
fore the  density  of  air  is  0.001293  or  yf$  that  of  water. 


46  MECHANICAL  UEFRIGERATION. 

One  hundred  cubic  inches  of  hydrogen,  the  lightest  of 
the  common  gases  weighs  2.14  grains. 

MIXTURE  OF  GASES. 

Two  or  more  gases  present  in  vessels,  communicat- 
ing with  each  other,  mix  readily,  and  each  portion  of  the 
mixture  contains  the  different  gases  in  the  same  pro- 
portion. Mixtures  of  gases  follow  the  same  laws  as 
simple  gases. 

DALTON'S  LAW. 

The  pressure  exerted  on  the  interior  walls  of  a  vessel 
containing  a  mixture  of  gases  is  equal  to  the  sum  of  the 
pressures  which  would  be  exerted  if  each  of  the  gases 
occupied  the  vessel  itself  alone. 

BUOYANCY  OF  GASES. 

The  Archimedian  principle  applies  also  for  gases; 
hence  a  body  lighter  than  air  will  ascend  (air  balloons, 
smoke,  etc.). 

LIQUEFACTION  OF  GASES. 

If  sufficient  pressure  be  applied  to  a  gas  and  the  tem- 
perature is  sufficiently  lowered  all  gases  can  be  com- 
pressed so  as  to  assume  the  liquid  state. 

HEAT  OF  COMPRESSION. 

When  gases  or  vapors  are  being  compressed,  the 
energy  or  work  spent  to  accomplish  the  compression 
appears  in  the  form  of  heat. 

CRITICAL  TEMPERATURE. 

There  appears  to  exist  for  each  gas  a  temperature 
above  which  it  cannot  be  liquefied,  no  matter  what 
amount  of  pressure  is  used.  It  is  called  the  critical  tem- 
perature. Below  this  temperature  all  gases  or  vapors 
may  be  liquefied  if  sufficient  pressure  is  used. 

CRITICAL  PRESSURE. 

The  pressure  which  causes  liquefaction  of  a  gas  at  or 
as  near  below  the  critical  temperature  as  possible,  is 
called  the  critical  pressure.  Between  these  two  tempera- 
tures— that  is,  in  the  neighborhood  of  the  critical  point — 
the  transition  from  one  state  to  another  is  unrecog- 
nizable. 

CRITICAL  VOLUME. 

The  critical  volume  of  a  gas  is  its  volume  at  the 
critical  point,  measured  with  its  volume  at  the  freezing 


FLUIDS;  GASES;  VAPORS. 


47 


point,  under  the  pressure  of  an  atmosphere  as  unit. 
The  critical  temperature,  pressure  and  volume  are  fre- 
quently referred  to  as  critical  data. 

TABLE  OF  CRITICAL  DATA. 


Substance. 

Critical  Press- 
ure in  Atmos- 
pheres. 

Critical  Tem- 
perature, 
Degrees  C. 

Critical 
Volume. 

Ammonia,    

115 

130 

Aethylen  

61 

10 

0.00560 

Alcohol    

67 

235 

0.00713 

Acetic  acid            

76.4 

231.5 

0.0110 

Aethylic  ether 

37.5 

200 

0  01344 

Acetate  of  aethyl.         . 

42.2 

240 

0  01222 

Benzol  

60 

292 

0.00981 

Bisulphide  of  carbon.. 
Butyrate  of  amyl  

77.8 
23.8 

275 
332 

0.0096 
0  03809 

Carbonic  acid 

77 

31 

0  0066 

Cumol    

31.8 

347.2 

0.0258 

Hydrogen          . 

20  3 

—240 

Nitrous  oxide  (N2O)... 

75 
50 

35.4 
—118 

0.00480 

Propylic  alcohol  

63.3 

256 

0.00968 

Sulphurous  acid         .  . 

79 

155  4 

Toluol    

40 

320.8 

0  02138 

Water    

195 

358 

0  00187 

SPECIFIC  HEAT  OF  GASES. 

A  gas  may  be  heated  while  its  volume  is  kept  con- 
stant and  also  while  its  pressure  remains  constant.  In 
the  former  case  the  pressure  increases  and  in  the  latter 
the  volume  increases.  Therefore  we  make  a  distinction 
between  specific  heat  of  gases  at  a  constant  volume  or 
at  a  constant  pressure.  In  the  former  case  the  heat 
added  is  only  used  to  increase  the  momentum  of  the 
molecules,  while  in  the  latter  case  an  additional  amount 
of  heat  is  required  to  do  the  work  of  expanding  the  gas 
against  the  pressure  of  the  atmosphere.  The  specific 
heat  of  all  permanent  gases  for  equal  volumes  at  con- 
stant pressure  is  nearly  the  same  and  about  0.2374  water 
taken  as  unity. 

TABLE  OF  SPECIFIC  HEAT  OF  GASES. 


For  Equal  Weights.       (Water  =  1.) 

At  Constant 
Pressure. 

At  Constant 
Volume. 

Air                                    .                   

.2377 
.2164 
.2479 
3.4046 
.5929 
.2440 
.2182 

.1688 
.1714 
.1768 
2.4096 
.4683 
.1740 
.1559 
.3050 
.3700 
.1246 

Carbonic  acid  (CO2)  

"        oxide  (CO) 

Hydrogen                         .         

Light  carbureted  hydrogen 

Nitrogen 

Oxygen    ^.             

Steam  saturated 

Steam  gas  .  .           

.4750 
.1553 

Sulphurous  acid 

48  MECHANICAL  REFRIGERATION. 

ISOTHERMAL  CHANGES. 

A  gas  is  said  to  be  expanded  or  compressed  isother- 
mally  when  its  temperature  remains  constant  during 
expansion  or  compression,  and  an  isothermal  curve  or 
line  represents  graphically  the  relations  of  pressure  and 
volume  under  such  conditions. 

ADIABATIC  CHANGES. 

As  gas  is  said  to  be  expanded  or  compressed  adiabat- 
ically  when  no  heat  is  added  or  abstracted  from  the  same 
during  expansion  or  compression,  an  adiabatic  line 
or  curve  represents  graphically  the  relations  of  pressure 
and  volume  under  such  conditions. 

FREE  EXPANSION. 

When  gas  expands  against  an  external  pressure 
much  less  than  its  own,  the  expansion  is  said  to  be  free. 
The  refrigeration  due  to  the  work  done  by  such  expansion 
may  be  used  to  liquefy  air.  (See  Linde's  method.) 

LATENT  HEAT  OF  EXPANSION. 

When  a  gas  expands  while  doing  work,  such  9« 
propelling  a  piston,  an  amount  of  heat  equivalent  to  tb« 
work  done  becomes  latent  or  disappears.  It  is  called  the 
latent  heat  of  expansion. 

VOLUME  AND  PRESSURE. 

The  relations  of  volume  pressure  and  temperature 
of  gases  are  embodied  in  the  following  formulae  in  which 
V  stands  for  the  initial  volume  of  a  gas  at  the  initial  tem- 
perature t  and  the  initial  pressure  p.  F1,  tt  and  j?» 
stand  for  the  corresponding  final  volume,  temperature 
and  pressure.  For  different  temperatures— 


=  V 

t+461 


For  different  pressures— 

V1  =  V-2-     i 
P1 

For  different  temperature  and  pressure— 


pM*  +461) 

If  the  initial  temperature  is  60°  F.  and  ^he  initial 
pressure  that  of  the  atmosphere,  the  final  pressure  may 
be  found  after  the  formula— 


FLUIDS;  GASES;  VAPORS.  49 


rl 

If  the  volume  is  constant — 

P1 


35.58 

If  the  temperatures  in  above  formula  are  expressed 
degrees  Fahrenheit  above  absolute  zero,  the  figure  461  is 
to  be  omitted. 

PERFECT  GAS. 

The  above  rules  and  formulae  apply,  strictly  speak- 
ing, only  to  a  perfect  or  ideal  gas,  that  is  a  gas  in  which 
the  dimensions  of  the  molecules  may  be  neglected  as  re- 
gards the  distance  between  them.  Therefore  when  a 
gas  approaches  the  state  of  a  vapor,  these  laws  do  no 
more  hold  good. 

ABSOLUTE  ZERO  AGAIN. 

The  expansion  of  a  perfect  gas  under  constant 
pressure  being  ^g  of  its  volume  at  32°  F.  (freezing 
point),  it  follows  that  if  a  perfect  gas  be  cooled  down  to 
a  temperature  of  493°  below  freezing,  or  461°  below  zero 
Fahrenheit,  its  volume  will  become  zero.  Hence  this 
point  is  adopted  as  the  absolute  zero  of  temperature. 
(See  also  former  paragraph  on  this  subject.) 

VELOCITY  OF  SOUND. 

The  velocity,  v,  of  sound  in  gases  is  expressed  by  the 
formula— 


In  which  formula  g  is  the  force  of  gravity,  h  the 
barometric  height,  d  the  density  of  mercury,  d  the 
density  of  the  gas,  t  its  temperature,  c  its  specific 
heat  at  constant  pressure,  and  ct  its  specific  heat  at  con- 

*  C 

stant  volume.  Hence  the  quotient,  — — ,  for  a  certain  gas 

^i 
can  be  determined  by  the  velocity  of  sound  in  the  same. 

FRICTION  OF  GAS  IN  PIPES. 

The  loss  of  pressure  in  pounds,  P,  sustained  by  gas 
in  traveling  through  a  pipe  having  the  diameter  d  in 
inches,  for  a  distance  of  I  feet,  and  having  a  velocity  of 
n  feet,  is — 

p  =  0.00936  !LiL 


50  MECHANICAL  REFRIGERATION 

ABSORPTION  OF  GASES. 

Gases  are  absorbed  by  liquids ;  the  quantities  of  gases 
so  absorbed  depend  on  the  nature  of  the  gas  and  liquid, 
and  generally  increase  with  the  pressure  and  decrease 
with  the  temperature.  During  the  absorption  of  gas  by 
a  liquid  a  definite  amount  of  heat  is  generated,  which 
heat  is  again  absorbed  when  the  gas  is  driven  from  the 
liquid  by  increase  of  temperature  or  decrease  of  pressure. 
Solids,  especially  porous  substances,  also  absorb  gases. 
Thus  charcoal  absorbs  ninety  times  its  own  volume  of 
ammonia  gas. 

VAPORS. 

As  long  as  a  volatile  substance  is  above  its  critical 
temperature  it  is  called  a  gas,  and  if  below  that  it  is 
called  a  vapor. 

This  definition,  although  the  most  definite  is  not  the 
most  popular  one.  Frequently  a  vapor  is  defined  as  rep- 
resenting that  gaseous  condition  at  which  a  substance 
has  the  maximum  density  for  that  temperature  or 
pressure.  Generally  gaseous  bodies  are  called  vapors 
when  they  are  near  the  point  of  their  maximum  density, 
and  a  distinction  is  made  between  saturated  vapor, 
superheated  vapor  and  wet  vapor. 

SATURATED  VAPOR. 

A  vapor  is  saturated  when  it  is  still  in  contact  with 
some  of  its  liquid;  vapors  in  the  saturated  state  are  at 
their  maximum  density  for  that  temperature.  Com- 
pression of  a  saturated  vapor,  without  change  of  tem- 
perature, produces  a  proportional  amount  of  liquefaction. 

DRY  OR  SUPERHEATED   VAPOR. 

Vapors  whieh  are  not  saturated  are  also  called  dry 
or  superheated  vapors,  and  behave  like  permanent  gases. 

WET  VAPOR. 

A  saturated  vapor  which  holds  in  suspension  parti- 
cles of  its  liquid  is  called  wet  or  moist  vapor. 

TENSION  OF  VAPORS. 

Like  gases,  vapors  have  a  certain  elastic  force,  by 
virtue  of  which  they  exert  a  certain  pressure  on  sur- 
rounding surfaces.  This  elastic  force  varies  with  the 
nature  of  the  liquid  and  the  temperature,  and  is  also 
called  the  tension  of  the  vapor, 


FLUIDS;  GASBS;  VAPORS  51 

VAPORIZATION. 

A  liquid  exposed  to  the  atmosphere  or  to  a  vacuum 
forms  vapors  until  the  space  above  the  liquid  contains 
vapor  of  the  maximum  density  for  the  temperature. 

EBULLITION. 

If  the  temperature  is  high  enough  the  vaporization 
takes  place  throughout  the  liquid  by  the  rapid  produc- 
tion of  bubbles  of  vapor.  This  is  called  ebullition,  and 
the  temperature  at  which  it  takes  place  is  a  constant 
one  for  one  and  the  same  liquid  under  a  given  pressure. 

BOILING  POINT. 

The  temperature  at  which  ebullition  of  a  liquid  takes 
place  is  called  its  boiling  point,  for  the  pressure  then  ob- 
taining. When  no  special  pressure  is  mentioned  we 
understand  by  boiling  point  that  temperature  at  which 
liquids  boil  under  the  pressure  of  the  atmosphere. 

DIFFERENT  BOILING  POINTS. 

The  boiling  point  varies  with  the  nature  of  the 
liquid,  and  always  increases  with  the  pressure.  It  is 
not  affected  by  the  temperature  of  the  source  of  heat, 
the  temperature  of  the  liquid  remaining  constant  as  long 
as  ebullition  takes  place.  »The  heat  which  is  imparted 
to  a  boiling  liquid,  but  which  does  not  show  itself  by 
an  increase  of  temperature,  is  called  the  latent  heat  of 
vaporization. 

ELEVATION  OF  BOILING  POINT. 

Substances  held  in  solution  by  liquids  raise  their 
boiling  point.  Thus  a  saturated  solution  of  common 
salt  boils  at  214°  and  one  of  chloride  of  calcium  at  370°. 
The  boiling  point  of  pure  water  may  also  be  raised  above 
the  boiling  point;  for  water  free  from  gases  to  over  260° 
without  showing  signs  of  boiling.  This  retardation  of 
boiling  sometimes  takes  place  in  boilers,  and  may  cause 
explosions,  if  not  guarded  against  by  a  timely  motion 
produced  in  the  water. 

LATENT  HEAT  OF  VAPORIZATION. 

The  heat  which  becomes  latent  during  the  process  of 
volatilization  is  composed  of  two  distinct  parts.  The  one 
part  is  absorbed  while  doing  the  work  of  disintegrating  the 
molecular  structure  while  doing  INTERNAL  WORK,  as  it  is 
termed.  The  other  part  of  heat  which  becomes  latent  is 


52  MECHANICAL  REFRIGERATION. 

absorbed  while  doing  the  work  of  expansion  against  the 
pressure  of  the  atmosphere,  and  is  called  the  EXTERNAL 
WORK.  In  a  liquid  evaporized  in  vacuum,  in  which  case 
no  pressure  is  to  be  overcome,  the  external  work  becomes 
zero,  and  only  heat  is  absorbed  to  do  the  internal  work 
of  vaporization  (free  expansion}. 

REFRIGERATING  EFFECTS. 

If  liquids  possess  a  boiling  point  below  the  tempera- 
ture of  the  atmosphere  the  latent  heat  of  vaporization  is 
drawn  from  its  immediate  surrounding  object,  causing  a 
reduction  of  temperature,  i.  e.,  refrigeration. 

LIQUEFACTION  OF  VAPORS. 

When  vapors  pass  from  the  aeriform  into  the  liquid 
state,  that  is,  when  they  are  liquefied,  the  heat  which  bo- 
came  latent  during  evaporation  appears  again,  and  must  I  e 
removed  by  cooling.  Vapors  of  liquids  the  boiling  point  i  ^f 
which  is  above  the  ordinary  temperature  can  be  liquefied 
at  the  ordinary  temperature  without  additional  pressure 
(distilling  condensation}.  Permanent  gases  require  addi- 
tional pressure,  and  in  some  cases  considerable  refrigera- 
tion, to  become  liquefied  (compression  of  gases). 

D ALTON'S  LAW  FOR  VAPORS. 

The  tension  and  consequently  the  amount  of  vapor 
of  a  certain  substance  which  saturates  a  given  space  is 
the  same  for  the  same  temperature,  whether  this  space 
contains  a  gas  or  is  a  vacuum.  The  tension  of  the  mix- 
ture of  a  gas  and  a  vapor  is  equal  to  the  sum  of  the  ten- 
sions which  each  would  possess  if  it  occupied  the  same 
space  alone. 

VAPORS  FROM  MIXED  LIQUIDS. 

The  tension  of  vapor  from  mixed  liquids  (which  have 
no  chemical  .or  solvent  action  on  each  other)  is  nearly 
equal  to  the  sum  of  tension  of  the  vapor  of  the  two 
separate  liquids. 

SUBLIMATION. 

The  change  of  a  solid  to  the  vaporous  state  without 
first  passing  through  the  liquid  state  is  called  sublimation 

(camphor,  ice). 

DISSOCIATION. 

The  term  dissociation  is  used  to  denote  the  separa- 
tion of  a  chemical  compound  into  its  constituent  parts, 
especially  if  the  separation  is  brought  about  by  subject- 
ing the  compound  to  a  high  temperature. 


MOLECULAR  DYNAMICS.  53 

CHAPTER  VI.—  MOLECULAR  DYNAMICS. 

MOLECULAR   KINETICS. 

It  has  already  been  stated  that  the  laws  of  Boyle 
and  St.  Charles  are  in  accordance  with  the  molecular 
theory,  by  the  consequent  development  of  which  a  num- 
ber of  other  relations  have  been  established  which  are  of 
the  utmost  importance  in  all  discussions  of  energy,  es- 
pecially those  of  thermodynamical  nature.  Applied  to 
gases,  this  theory  means  that  the  rectilinear  progressive 
motion  of  the  molecules,  which  constitutes  the  body  of  a 
gas,  represents  by  its  kinetic  energy  the  temperature  of 
a  gas,  and  by  the  number  of  impacts  of  its  molecules 
against  the  wall  of  the  vessel  containing  the  gas,  its 
pressure. 

DENSITY  OF  GASES. 

If  m  represents  the  mass  of  a  molecule  and  u  the 
average  velocity  of  its  rectilinear  progressive  motion,  the 
kinetic  energy,  E  (i.e.,  the  temperature),  of  the  molecule 
is  expressed  by  — 


If  the  unit  of  volume,  say  a  cubic  foot  of  a  gas,  con- 
tains JV  molecules  of  the  mass,  m,  the  density  of  the 
gas,  p,  is— 

p=  m  N 

PRESSURE  OF  GASES. 

The  number  of  molecules  which  collide  with  the  inte- 
rior surf  aces  of  a  cube  of  above  size  is  equal  to  N  it,  and 
hence  the  number  which  collide  with  one  of  the  interior 
surfaces  of  the  cube  (one  foot  square): 

Nu 

6 

The  number  of  impacts  multiplied  by  the  momentum 
of  the  impact  of  each  molecule,  2  ra  it,  yields  the  pressure: 

p  =  -^-Nmu2  =  ^-puz 

o  o 

AVOGADRO'S  LAW. 

At  the  same  temperature  and  pressure  equal  volumes 
of  different  gases  contain  the  same  number  of  molecules. 
Hence  the  molecular  weights  of  gases  are  proportional  to 
their  densities, 


54  MECHANICAL  REFRIGERATION. 

MOLECULAR  VELOCITY. 

The  average  velocity  of  the  molecules,  ut  is  accord- 
ingly— 


For  hydrogen  we  find  u  =  1,842  meters  per  second. 

If  M  is  the  molecular  weight  of  a  gas  referred  to 
hydrogen  as  unit  (p  being  proportional  to  M)  the  aver- 
age velocity  of  the  molecules  is  expressed  by— 


u  =  1,842  -*  /   -±_  meters  per  second. 
\     M 

The  average  distance,  L,  which  a  molecule  travels  in  rec- 
tilinear direction  before  it  meets  another  molecule  is  ex- 
pressed by  the  formula— 

L==  1.41  ics* 

in  which  \  is  the  average  distance  of  the  molecules,  and 
therefore  A.3  the  size  of  the  cube  which  contains  one 
molecule  on  an  average. 

L  accordingly  has  been  found  to  be  for  hydrogen 
0.000185  millimeter;  for  carbonic  acid,  0.000068mm.;  for 
ammonia  0.000074  mm. 

INTERNAL  FRICTION  OF  GASES. 

The  internal  friction,  77,  of  a  gas  is  expressed  by  the 
equation— 


The  velocity  of  sound  in  different  gases  is  inversely 
proportional  to  the  square  root  of  their  molecular 
weights  (see  page  49). 

TOTAL  HEAT  ENERGY  OF  MOLECULES. 

The  total  heat  energy  of  a  body  is  composed  of  the 
energy  due  to  the  progressive  motion  of  its  molecules, 
and  the  interior  energy  which  is  represented  by  possible 
rotatory  motions  of  the  molecules,  or  by  motions  of  the 
atoms  composing  the  molecule.  In  gases,  and  probably 
also  in  liquids  and  solid  bodies,  the  former  portion  of 
energy  is  proportional  to  the  absolute  temperature,  so 
that  at  the  absolute  zero  —461°  F.—  the  progressive  mo- 
tion of  the  atoms  would  cease. 


MOLECULAR  DYNAMICS.  55 

LAW  OF  GAY  LUSSAC. 

Since  chemical  combinations  between  different  ele- 
ments take  place  in  the  proportion  of  their  molecular 
weights,  and  since  equal  volumes  of  gases  contain  equal 
numbers  of  molecules,  the  chemical  combination  between 
gaseous  elements  must  take  place  by  equal  volumes  or 
their  rational  multiples,  and  the  volume  of  the  combina- 
tion if  gaseous  bears  equally  a  simple  numerical  relation 
to  that  of  the  elements. 

EXPANSION  OP  GASES. 

Since  the  same  number  of  molecules  of  different 
gases  occupy  the  same  volume  at  equal  temperatures  and 
pressure,  the  expansion  by  heat  of  all  gasec  under  con- 
stant pressure  must  be  the  same,  and  for  perfect  gases  it 
is  the  same  for  all  temperatures,  being  equal  to  the  ^5 
part  of  the  volume  of  a  gas  at  the  freezing  point  and  at 
the  pressure  of  one  atmosphere.  This  is  tantamount  to 
saying  that  the  volume  of  gas  under  constant  pressure  is 
proportional  to  its  absolute  temperature,  T=  461  -f-  *• 

EQUATION  FOR  PERFECT  GASES. 

The  increase  of  pressure  of  a  gas  heated  at  constant 
volume  being  likewise  proportional  to  the  absolute  tem- 
perature and  equal  to  ^  of  its  volume  at  the  freezing 
point,  the  product  of  pressure  and  volume,  p  v,  must  be 
likewise,  and  hence  it  can  be  expressed  by  the  equation— 

p  v  =  E  T 

in  which  R  is  a  constant  factor,  depending  only  upon  the 
units  used.  T  standing  for  absolute  temperature,  it  may 
be  written— 


p0  and  v0  standing  for  pressure  and  volume  at  the  tem- 
perature of  32°  F.,  both  being  unit. 

GENERAL  EQUATION  FOR  GASES  AND  LIQUIDS.   . 

Tnis  formula  answers  for  a  perfect  gas  in  which  the 
dimension  of  the  molecules  and  their  mutual  attraction 
disappear  in  comparison  with  their  volume  and  the 
expansive  force  due  to  the  temperature.  If  the  dimen- 
sions and  mutual  attraction  are  taken  into  consideration, 
the  formula  according  to  Van  der  Waals  reads: 


56  MECHANICAL  REFRIGERATION. 

In  this  formula  the  signs  have  the  same  meaning  as 
in  the  former  equation,  except  the  two  constants  a  and 

6,  which  differ  with  the  nature  of  the  gas  ~\  atoning  for 

the  influence  of  the  molecular  attraction  which  may  be 
derived  from  the  deviation  of  the  gas  from  Boyle's  law; 
b  stands  for  the  influence  of  the  volume  of  the  molecule; 
it  is  equal  to  four  times  the  volume  of  the  molecules. 
Its  value  may  be  ascertained  by  inserting  the  value 
found  for  a  into  the  formula  of  Van  der  Waals.  How- 
ever, it  is  generally  more  convsnient  and  of  more  prac- 
tical application  to  derive  the  values  a  and  b  from  the 
critical  data,  as  will  be  shown  later  on. 

The  formula  of  Van  der  Waals  answers  not  only  for 
all  gases,  but  for  the  liquid  condition  as  well,  as  far  as 
changes  of  volume,  pressure  and  temperature  are  con- 
cerned, provided,  however,  that  the  changes  take  place 
homogeneously  and  that  the  molecular  constitution  of 
the  substance  is  not  altered  during  the  change. 

CRITICAL  CONDITION. 

If  this  formula  is  elaborated  numerically  as  to  vol- 
ume for  given  temperatures  and  pressures,  we  always 
obtain  one  real  positive  expression  for  volume  except 
for  pressures  near  the  point  of  liquefaction  at  tempera- 
tures below  the  critical  point. 

Here  the  formula  does  not  apply  on  account  of  the 
so-called  critical  condition  (partly  gas  and  partly  liquid) 
which  the  substance  maintains  at  this  stage. 

These  conditions  become  readily  apparent  by  an 
elaboration  of  the  equation  of  Van  der  Waals,  for  if  the 
equation— 


which  may  also  be  written— 


is  developed  after  powers  of  v  (  p0  and  v0  =  unit),  we 
obtain— 


This  equation  being  a  cubical  one,  it  may  be  satisfied 
by  three  values,  which  may  all  be  real  or  one  of  which 
may  be  real  and  the  other  two  imaginary.  Accordingly,  we 


MOLECULAR  DYNAMICS.  57 

find  for  all  temperatures  above  the  critical  point  for 
any  given  pressure  only  one  value  for  volume  ;  except 
for  temperatures  below  the  critical  point  for  certain 
values  of  p,  i.e.,  for  pressures  near  the  point  of  lique- 
faction for  that  temperature,  or  nearing  the  boiling 
point  for  that  pressure.  At  these  stages  the  substance 
is  under  so-called  critical  conditions,  and  here  we  find 
three  different  values  for  v,  one  of  which  may  stand  for 
the  volume  of  the  substance  in  its  gaseous  form,  another 
for  its  volume  as  a  liquid,  and  the  third  for  an  inter- 
mediate volume 

CRITICAL  DATA. 

When,  on  increasing  temperature  and  pressure  these 
three  values  for  volume  converge  into  one,  that  is,  if  the 
three  real  roots  of  the  equation  become  equal,  we  have 
reached  the  critical  volume,  that  is,  that  volume  which 
corresponds  to  the  critical  pressure  and  to  the  critical 
temperature.  At  this,  the  critical  point,  the  substance 
passes  gradually  and  without  showing  a  separation  into 
liquid  and  gas,  that  is  to  say  homogeneously,  from  the 
gaseous  into  the  liquid  state;  there  is  no  intermediate 
stage  at  this  temperature  between  the  volume  of  the 
liquid  and  the  volume  of  the  gas,  as  is  the  case  at  tem- 
peratures below  the  critical  point  and  at  pressures  cor- 
responding to  the  boiling  point. 

The  values  of  temperature  pressure  and  volume  at 
which  the  three  roots  of  the  above  equation  become 
equal  is  found  by  the  following  considerations:  If  in  a 
cubical  equation  of  the  form  — 


the  three  roots  become  equal  to  each  other  =  xt  the  fol- 
lowing relations  obtain  : 


Applying  this  to  the  above  equation,  which  may  also 
be  written  — 


by  inserting  the  signs,  q>,  n  and  5  to  stand  for  volume, 
pressure  and  temperature  at  the  critical  point  we  find— 


68  MECHANICAL  BEFKIGERATION. 

*~ 


which  may  be  simplified  thus: 
^=3  6 


^  __  8  o       493 

27     (1  +  a)  b  (1—6) 

We  see  from  these  formulae  how  the  two  constants, 
a  and  6,  which  may  be  deduced  from  the  deviations  from 
Boyle's  law,  determine  the  critical  pressure,  temperature 
and  volume. 

APPLICATION  OF  GENERAL  EQUATION. 

On  the  other  hand  (and  which  is  practically  of  more 
importance),  it  is  readily  seen  how  the  two  constants,  a 
and  6,  and  therefore  the  behavior  of  a  homogeneous  gas 
or  liquid  as  to  volume,  temperature  and  pressure,  may 
be  derived  from  the  critical  data,  viz.  : 


3  S  _  it  <p  493 

8        r*  •»  *.•.''•  -*,v-y-«       <p  \ 


The  last  equation  may  be  rendered  approximately  by 

_87T<?493_      8a 
27  6 


The  numerical  values  for  a  and  b  for  any  substance 
having  been  ftmnd  by  these  formulse  from  the  critical 
temperature  and  pressure,  they  may  be  inserted  in  the 
general  equation  of  Van  der  Waals,  which  will  then  yield 
the  relations  of  pressure  and  volume  at  different  temper- 
atures, etc. 


MOLECULAR  DYNAMICS.  50 

UNIVERSAL  EQUATION. 

If  the  volume,  pressure  and  temperature  of  a  gas 
are  measured  by  fractions  of  the  absolute  data,  in  other 
words,  if  v  —  n  q>  and  p  =  e  it  and  T—  m  £,  the  general 
equation  may  be  written  — 


If  the  values  for  TT,  <p  and  S  as  found  in  the  above, 
are  inserted  in  this  equation  the  same  may  be  brought 
to  the  f  orm— 


This  formula  contains  no  terms  dependent  upon  the 
nature  of  the  substance,  hence  the  equation  establishing 
the  relations  between  pressure,  volume  and  temperature 
is  the  same  for  all  substances,  if  volume,  pressure  and 
temperature  are  expressed  in  fractions  of  the  critical 
data  (provided  v  >  46). 

If  v  is  smaller  than  4  b  the  formula  may  possibly  give 
correct  results,  but  when  it  does  not  such  a  result  does 
not  vitiate  the  admissibility  of  the  theory  in  other  re- 
spects, as  Van  der  Waals  has  shown. 

OTHER  MOLECULAR  DIMENSIONS. 

In  accordance  with  the  foregoing  the  average  space, 
Y,  occupied  by  each  molecule  of  a  gas  is  expressed  by— 

y-     JL  ** 

4  32  X  273  it 

and  the  specific  weight,  w,  of  a  gas  (water  at  39°  F.  =  1): 

M 

22350  y 

M  being  the  molecular  weight  in  grams,  and  22,350  c.  c. 
the  volume  occupied  by  the  same  at  32PF.,  and  at  the 
pressure  of  one  atmosphere. 

If  the  molecules  are  supposed  to  be  of  spherical  form 
their  diameter,  s,  is  expressed  by  the  formula— 

s  =  6  V~2~I,  y  =  8.5  L  y 

L  being  the  average  distance  which  a  molecule  travels, 
as  stated  above,  viz.  : 

L  --  »  _ 

V2      7TS2 


60  MECHANICAL  REFRIGfiRATloK. 

ABSOLUTE  BOILING  POINT. 

The  definition  of  the  boiling  point  as  given  hereto- 
fore fits  only  for  a  certain  pressure,  but  in  accordance 
with  the  critical  conditions  we  can  define  an  absolute 
boiling  point  as  the  temperature  at  which  a  liquid  will 
assume  the  aeriform  state,  ho  matter  what  the  press- 
ure is,  viz.,  the  critical  temperature. 

CAPILLARY  ATTRACTION. 

Since  capillary  attraction  (in  consequence  of  which 
liquids  rise  above  their  surface  in  narrow  tubes)  and  also 
the  surface  tension  of  liquids  are  both  functions  of  the 
cohesion  of  liquids,  and  since  the  cohesion  diminishes 
with  the  temperature,  the  capillary  attraction  must  do 
likewise;  and  it  has  been  shown  that  it  becomes  zero  at 
the  critical  temperature  or  at  the  absolute  boiling  point. 

CRITICAL  VOLUME. 

At  the  critical  temperature  the  change  from  the 
liquid  to  the  gaseous  condition  requires  no  interior 
work,  and  therefore  the  latent  heat  of  vaporization  at 
this  temperature  must  be  equal  to  zero. 

The  volumes  of  a  certain  weight  of  liquid  or  vapor  of 
a  substance  at  the  critical  temperature  must  likewise  be 
the  same. 

GAS  AND  VAPOR. 

If,  with  Andrews,  we  confine  the  conception  of  vapor 
to  a  fluid  below  its  critical  point,  and  that  of  a  gas  to  a 
fluid  above  its  critical  point,  we  can  also  define  as  vapor 
such  aeriform  fluids  as  may  be  compressed  into  a 
liquid  by  pressure  alone  without  lowering  temperature; 
and  by  the  same  token  a  gas  is  an  aeriform  fluid  which 
cannot  be  compressed  into  a  liquid  by  pressure  alone 
without  lowering  the  temperature.  By  liquefaction  we 
designate  the  production  of  a  liquid  separated  from  the 
vapor  by  a  visible  surface. 

LIQUEFACTION  OF  GASES. 

After  the  significance  of  the  critical  temperature 
had  been  duly  understood  and  appreciated  it  became 
also  possible  to  liquefy  the  most  refrangible  gases  by 
pressure  when  cooled  down  below  their  critical  tempera- 
ture. A  novel  way  for  the  liquefaction  of  such  gases, 
more  especially  air,  has  been  devised  by  Linde,  and  the 
process  employed  by  him  is  so  simple  and  successful  that 
it  will  doubtless  become  of  practical  value  in  many  re- 
spects, more  especially  also  practical  refrigeration. 


THERMODYNAMICS.  6l 

CHAPTER  VII.— THERMODYNAMICS. 

THERMODYNAMICS. 

Thermodynamics  as  the  science  which  treats  of  heat 
in  relation  to  other  forms  of  energy,  and  more  especially 
of  the  relations  between  heat  and  mechanical  energy. 

FIRST  LAW  OF  THERMODYNAMICS. 

This  law  is  a  special  case  of  the  general  law  express- 
ing the  convertibility  of  different  forms  of  energy  into 
one  another.  The  first  law  of  thermodynamics  asserts 
the  equivalence  of  heat  and  work  or  mechanical  energy, 
and  states  their  numerical  relation.  Accordingly  heat 
and  work  may  be  converted  into  each  other  at  the  rate 
of  778  foot-pounds  for  every  unit  of  heat,  and  vice  versa. 

SECOND  LAW  OF  THERMODYNAMICS. 

The  foregoing  law  holds  good  without  any  limitation 
as  far  as  the  conversion  of  work  or  mechanical  energy 
into  heat  is  concerned.  It  must  be  qualified,  however,  with 
respect  to  the  conversion  of  heat  into  work.  It  amounts 
to  this,  that  of  a  certain  given  amount  of  heat  at  a  given 
temperature  only  a  certain  but  well  defined  portion  can 
be  converted  into  work,  while  the  remaining  portion  must 
remain  unconverted  as  heat  of  a  lower  temperature. 
This  outcome  is  a  natural  consequence  of  the  condition 
that  heat  cannot  be  directly  transferred  from  a  colder  to  a 
warmer  body. 

EQUIVALENT  UNITS. 

In  accordance  with  the  first  law,  we  can  measure 
quantities  of  heat  by  the  heat  unit  or  by  the  unit  of  work 
(foot-pound)  and  we  can  also  measure  it  by  its  equivalent 
in  heat  units  as  well  as  by  the  units  of  work.  The  figure 
designating  the  number  of  foot-pounds  equivalent  to  the 
unit  of  heat  (778),  i.  e.,  the  mechanical  equivalent  of  heat, 
is  frequently  referred  to  by  the  letter  J. 

When  quantities  of  work  and  heat  are  brought  in 
juxtaposition  in  equations,  etc.,  it  is  always  understood 
that  they  are  expressed  by  the  same  units,  i.  e.,  in  either 
heat  or  work  units. 

SECOND  LAW  QUALIFIED. 

In  a  system  in  which  the  changes  are  only  such  of 
heat  and  such  of  mechanical  energy  (work),  the  appear- 
ance of  a  certain  amount  of  work  is  always  accompanied 
by  the  disappearance  of  an  equivalent  amount  of  heat, 


62  MECHANICAL  REFRIGERATION. 

and  the  appearance  of  a  certain  amount  of  heat  is  always 
accompanied  by  the  expenditure  of  an  equivalent  amount 
of  mechanical  energy.  From  this,  however,  it  must  not 
be  concluded  that  by  withdrawing  a  certain  amount  of 
heat  from  a  warmer  body  we  can  convert  it  into  its 
equivalent  amount  of  mechanical  energy.  This  is  only  the 
case  under  exceptional  conditions ;  but  when,  as  in  the 
case  of  practical  requirements,  the  conversion  of  heat 
into  work  must  be  done  by  a  continuous  process  it  cannot 
be  accomplished  under  conditions  practically  available. 

CONVERSION  OF  HEAT. 

The  conversion  of  heat  into  mechanical  work,  and 
work  into  heat,  takes  place  in  many  ways.  Generally  the 
change  of  volume  or  pressure  brought  about  by  heat 
changes  mediates  the  conversion.  The  substance  which 
is  used  to  mediate  the  conversion  is  called  the  working 
medium  or  the  working  substance. 

MOLECULAR  TRANSFER  OF  HEAT  ENERGY. 

The  manner  in  which  heat  is  converted  into  mechan- 
ical work  is  readily  understood  on  the  basis  of  the  molec-' 
ular  theory,  when  the  working  fluid  is  a  gas,  the  pressure 
of  which,  due  to  its  molecular  energy  (heat)  is  employed 
to  propel  a  piston.  The  molecules  of  the  gas  by  colliding 
with  the  piston  impart  a  portion  of  their  molecular 
energy  to  the  piston,  moving  the  same  forward;  at  the 
same  time  the  energy  of  the  molecules  grows  less,  and 
indeed  the  temperature  of  the  gas  decreases  as  the  piston 
moves  ahead.  If  the  work  done  by  the  piston  and  the 
heat  lost  by  the  gas  were  measured  in  the  same  units, 
it  would  be  found  that  they  were  practically  alike  (pre- 
supposing we  employ  a  perfect  gas,  consisting  of  simple 
molecules,  undergoing  no  internal  changes). 

GAS  EXPANDING  INTO  VACUUM. 

If  there  had  been  no  pressure  on  the  piston  (and  the 
piston  supposed  to  have  no  weight)  in  the  foregoing 
experiment,  the  piston  would  have  been  moved  by  the 
expanding  gas,  without  doing  work  during  the  expansion, 
and  hence  the  temperature  of  the  gas,  while  expanding 
under  such  conditions  (against  a  vacuum),  remains  con- 
stant and  unchanged,  at  least  practically  so. 

HEAT  ENERGY  OF  GAS  MIXTURES. 

The  same  would  happen  if  two  vessels,  containing 
the  same  or  different  gases  at  different  pressures,  are 


THERMODYNAMICS.  63 

brought  in  communication ;  no  change  of  heat  takes 
place,  while  the  pressures  equalize  themselves.  Hence, 
the  heat  energy  of  a  gas  is  independent  of  its  volume,  and  the 
energy  of  a  mixture  of  gases  is  equal  to  the  sum  of  the  energy 
of  its  constituents. 

DISSIPATION  OF  ENERGY. 

Accordingly  we  may  allow  a  gas  under  pressure  to 
dilate  in  such  a  way  as  to  do  a  certain  amount  of  work 
at  the  expense  of  an  equivalent  amount  of  heat,  and  we 
may  allow  it  to  expand  without  doing  work.  In  the 
latter  case  the  availability  of  the  gas  to  mediate  a  cer- 
tain amount  of  work  has  not  been  utilized,  has  been  dis- 
sipated, as  it  were,  since  the  original  condition  of  the 
gas  cannot  be  re-established  again  without  the  expendi- 
ture of  outside  energy. 

ADIABATIC   CHANGES. 

In  the  former  case,  when  the  gas  was  allowed  to  ex- 
pand while  doing  work,  the  greatest  possible  amount  of 
work  obtainable  is  produced  when  the  pressure  of  the 
piston  is  always  kept  inflnitesimally  less  than  that  of 
the  gas.  If  this  is  being  done  the  original  condition  of 
the  gas  can  be  established  by  making  the  pressure  on 
the  piston  only  infinitesimally  more  than  on  the  gas, 
when  the  gas  will  be  compressed  to  its  original  volume 
and  temperature  (no  heat  having,  been  added  to  or  ab- 
stracted from  the  gas  during  the  operation).  Both  the 
operations  of  expansion  and  compression  of  the  gas  as 
conducted  (without  addition  of  heat,  etc.)  are  therefore 
adiabatic  changes,  they  are  both  reversible  changes,  and 
neither  of  them  involves  any  dissipation  of  heat  or 
energy.  In  the  one  change  we  have  converted  heat 
energy  into  work,  and  in  the  other  work  into  heat. 

ISOTHERMAL  CHANGES. 

The  expansion  of  the  gas  while  propelling  a  piston 
may  be  allowed  to  proceed  while  the  energy  imparted  to  the 
piston  is  replaced  by  heat  supplied  to  the  expanding  gas 
from  without.  In  this  case  the  expanding  gas  is  kept  at 
the  same  temperature,  and  therefore  it  is  said  that  the 
expansion  proceeds  isothermically.  This  operation  may 
also  be  reversed  and  work  converted  into  heat  by  apply- 
ing the  power  gained  by  raising  the  piston,  to  push 
the  piston  back,  and  withdrawing  the  beat  liberated  by 


64  MECHANICAL  REFRIGERATION. 

the  work  of  compression  as  fast  as  it  appears,  so  that 
the  gas  is  always  at  the  same  temperature.  (Isothermic 
compression.)  If,  during  expansion,  the  temperature  of 
the  gas  is  always  only  inflnitesimally  smaller,  and  dur- 
ing compression  infinitesimally  greater  than  the  out- 
side temperature,  both  operations  are  considered  to  be 
reversible,  and  no  dissipation  of  energy  takes  place  dur- 
ing the  performance  of  either  of  them. 

MAXIMUM  CONVERSION. 

In  conducting  the  operations  in  the  foregoing  (re- 
versible) manner  we  obtain  the  maximum  yield  of  mutual 
conversion  of  work  and  heat  obtainable  by  the  expansion 
or  compression  of  the  gas  in  question. 

CONTINUOUS  CONVERSION. 

While  a  body  of  gas  may  be  used  in  the  above  way 
to  convert  a  certain  amount  of  heat  into  work,  and  w«e 
versa,  it  would  not  answer  for  the  continuous  conversion 
of  work  into  heat,  for  if  the  operation  of  work  produc- 
tion is  reversed  we  simply  re-establish  the  original  con- 
dition without  having  accomplished  any  outside  change 
whatever. 

PASSAGE  OF  HEAT. 

The  fact  that  heat  cannot  of  itself  pass  from  a  colder 
to  a  warmer  body  is  also  in  harmony  with  the,  molecular 
theory.  The  molecules  of  bodies  having  the  same  tem- 
perature possess  also  the  same  average  energy,  and 
therefore  cannot  impart  energy  to  one  another;  much 
less  can  energy  of  heat  pass  from  a  colder  to  a  warmer 
body.  The  ability  of  heat  to  do  work  is  due  to  its  nat- 
ural tendency  to  pass  from  a  warmer  to  a  colder  body, 
and  therefore,  other  circumstances  being  equal,  is  di- 
rectly proportional  to  the  difference  of  temperature  be- 
tween the  warmer  and  colder  body. 

REQUIREMENTS  FOR  CONTINUOUS   CONVERSION. 

As  stated,  for  the  practical  conversion  of  heat  into 
work,  we  need  a  working  medium  that  is  a  substance  of 
some  kind  which  mediates  the  conversion.  As  the  heat 
which  is  communicated  to  this  medium  for  the  purpose 
of  doing  work  is  never  entirely  available  for  this  purpose, 
but  a  portion  of  the  heat  always  remains  as  heat  of  a 
lower  temperature  (not  available  for  mechanical  work 
except  when  it  can  pass  to  a  temperature  still  lower),  it  fol- 
lows as  a  matter  of  course  and  also  of  necessity,  that  when 


THERMODYNAMICS.  65 

we  desire  to  convert  heat  into  work  by  a  continuous  pro- 
cess we  need  not  only  a  working  substance  but  also  a 
warm  body,  a  source  of  heat  (boiler,  generator,  etc.),  and 
a  body  of  lower  temperature,  to  which  the  heat  not  avail- 
able for  work  in  the  operation  may  be  discharged.  The 
latter  device  is  generally  called  a  refrigerator  or  con- 
denser; in  the  case  of  many  heat  engines  it  is  the  atmos- 
phere. The  same  requirements,  only  in  a  reversed  order, 
obtain  for  the  continuous  conversion  of  work  into  heat, 
i.  e.,  when  heat  is  to  be  transferred  from  a  colder  to  a 
warmer  body,  the  work  expended  compensating  for  the 
transfer  (lifting  heat). 

COMPONENTS  OF  HEAT  CHANGES. 

The  changes  produced  in  a  body  by  heat  may  be 
divided  in  several  parts,  viz.,  the  elevation  of  tempera- 
ture, i.  e.,the  increase  of  energy  of  the  molecules,  the 
change  produced  by  overcoming  the  interior  cohesion, 
and  by  rearranging  the  molecular  constitution  of  the  body, 
and  the  change  required  to  do  outside  work,  overcoming 
pressure. 

MAXIMUM  CONTINUOUS  CONVERSION  OF  HEAT. 

The  question  as  to  the  maximum  amount  of  work 
which  can  be  obtained  from  a  certain  amount  of  heat  by 
continuous  conversion,  and  the  maximum  amount  of 
heat  which  can  be  obtained  by  or  lifted  by  a  certain 
amount  of  work,  is  one  of  the  most  important  in  ther- 
modynamics. It  has  been  solved  with  the  same  result  in 
various  ways,  the  following  giving  the  outlines  of  one  of 
them. 

CYCLE  OF  OPERATIONS. 

The  contrivances  which  are  required  to  perform  the 
operations,  by  which  through  the  aid  of  the  working 
medium,  etc.,  heat  is  continuously  transformed  into 
work,  or  work  into  heat,  come  under  the  general  head  of 
machines.  A  series  of  operations  of  the  kind  mentioned 
which  are  so  arranged  that  the  working  substance  returns 
periodically  to  its  original  condition  is  also  called  a  cycle 
of  operations. 

REVERSIBLE  CYCLE. 

If  a  cycle  of  operations  is  conducted  in  such  a  manner 
that  all  the  changes  or  operations  can  be  carried  out  in 
the  opposite  direction  the  cycle  is  what  is  called  a  revers- 
ible cycle.  Operations  can  generally  be  made  revers- 


OF  THE 
Mkil\/r-r->.~ 


66  MECHANICAL  REFRIGERATION. 

ible,  at  least  in  theory,  if  the  transfers  of  heat  follow 
only  infinitesimally  small  differences  in  temperature  and 
the  changes  in  volume  take  place  under  but  infinites- 
imally  small  differences  of  pressure.  Not  all  changes 
can  be  performed  in  a  reversible  manner,  however. 

IDEAL    CYCLE. 

For  the  continuous  conversion  of  heat  into  work  we 
require  the  performance  of  a  cycle,  so  that  the  work- 
ing substance,  which  is  generally  not  unlimited,  may 
return  periodically  to  its  original  condition,  and  may  be 
used  continuously  over  and  over  again.  If  at  the  same 
time  the  operations  of  the  cycle  are  carried  on  re- 
versibly  the  conversion  of  heat  into  work  takes  place  at 
the  greatest  possible  rate.  In  other  words,  the  maximum 
amount  of  work  obtainable  from  a  given  amount  of  heat 
is  realized  if  the  working  substance  is  passed  through  the 
operations  of  a  reversible  cycle.  Practically  we  can  only 
approach  the  conditions  of  a  reversible  cycle,  for  which 
reason  it  is  also  called  an  ideal  cycle  of  operations. 

IDEAL  CYCLES  HAVE  THE  SAME  EFFICIENCY. 

The  proof  that  a  cycle  of  reversible  operations  for 
the  transformation  of  heat  into  work  yields  the  greatest 
return  of  work  for  a  given  amount  of  heat,  and  vice  versa, 
may  be  based  on  the  axiom  that  no  energy  can  be 
created,  or  on  the  fact  that  heat  cannot  pass  from  a  colder 
to  a  warmer  body.  For  if  one  cycle  of  reversible  opera- 
tions would  yield  a  greater  amount  of  work  for  a  certain 
amount  of  heat  than  another  reversible  cycle,  the  latter 
would  also  by  reversing  it  require  a  lesser  amount  of 
work  to  produce  that  given  amount  of  heat.  Hence  we 
could  operate  the  first  cycle  to  convert  a  given  amount,  C, 
of  heat  to  produce  a  certain  amount  of  work,  B,  and  the 
second  cycle,  being  operated  in  the  reverse  manner, would 
only  need  a  portion  of  the  workB,  say  J5t,  to  reproduce 
the  heat  C,  which  could  be  employed  in  the  first  cycle  to 
again  produce  the  work  B.  Therefore  both  devices  or 
cycles  co-operating  in  the  manner  indicated  would  during 
each  co-operative  performance  create  the  work.B — Bt,  or 
rather,  transfer  an  equivalent  amount  of  heat  from  a 
colder  to  a  warmer  body,  which  is  impossible.  Hence  both 
devices  must  operate  with  the  same  efficiency,  and  all 
reversible  cycles  devised  for  the  mutual  conversion  of 
heat  into  work  must,  theoretically  speaking,  have  the 
same  efficiency,  and  the  maximum  efficiency  at  that. 


THERMODYNAMICS.  67 

INFLUENCE  OF  WORKING  FLUID. 

In  the  same  manner  it  may  be  demonstrated  that  the 
nature  of  working  substance  has  no  influence  upon  the 
amount  of  work  which  can  be  obtained  from  a  given 
amount  of  heat  in  a  reversible  cycle.  For  if  one  sub- 
stance could  be  employed  to  yield  a  greater  amount  of 
work  from  the  same  amount  of  heat  than  another  sub- 
stance, and  vice  versa,  a  combination  between  two  cycles, 
each  one  employing  one  of  the  two  substances,  could  be 
formed  like  the  above,  which  would  create  the  same  im- 
possible results. 

It  should  be  noted  that  this  deduction  holds  good 
only  when  the  two  cycles  work  between  the  same  limits 
of  temperature,  and  when  no  molecular  changes  take 
place  in  the  working  fluid,  the  mass  of  the  latter  remain- 
ing constant. 

RATE  OF  CONVERTIBILITY  OF  HEAT. 

The  maximum  amount  of  work  derivable  from  a 
given  amount  of  heat  in  a  continuous  cycle  of  operations, 
being  accordingly  independent  of  the  nature  of  the  work- 
ing  substance,  and  obtainable  by  every  ideal  reversible 
cycle,  the  rate  of  maximum  conversion  may  be  deduced 
from  the  working  of  any  such  cycle  of  operations. 
To  do  this  we  select  as  the  working  substance  in  our 
ideal  cycle  a  perfect  gas,  since  the  laws  governing  the 
relation  of  pressure,  temperature  and  volume  in  this 
case  are  not  only  well  known  but  also  comparatively 
simple.  The  first  ideal  reversible  cycle  of  operations  to 
determine  the  maximum  convertibility  of  heat  has  been 
devised  by  Carnot,  to  whom  the  original  elaborations  of 
this  subject  are  due.  Of  course  any  reversible  cycle 
answers  also.  For  simplicity's  sake,  following  the  example 
of  Nernst,  we  use  a  cycle  which  is  to  be  considered  re- 
versible when  working  between  very  small  differences  of 
temperatures  (between  boiler  and  refrigerator). 

SYNOPSIS  OF  NUMERICAL  PROOF. 

Consequently  we  assume  that  the  absolute  tempera- 
ture, Tlt  of  the  boiler  or  generator  is  only  a  little  higher 
than  the  temperature,  T0,  of  the  refrigerator,  when  the 
working  of  our  ideal  cycle  and  its  numerical  theoretical 
result  may  be  delineated  as  follows:  The  mechanical  de- 
vice consists  of  an  ideal  cylinder  provided  with  a  movable 
piston  containing  a  certain  amount  of  a  permanent  gas  of 


68  MECHANICAL  REFRIGERATION. 

the  volume  yx.  The  cylinder  is  immersed  in  the  refrig- 
erator of  the  temperature  TQ,  and  by  forcing  down  the 
piston  (reversibly)  is  compressed  to  the  smaller  volume 
vz.  The  work,  A,  required  to  perform  this  change  is  ex- 
pressed by —  .  _  p  j,  v, 

R  being  the  constant  of  the  gas  formula  as  above  de- 
fined, and  In  standing  for  natural  logarithm. 

As  the  temperature  is  to  remain  constant,  an  amount 
of  heat,  Q,  equivalent  to  the  work  done  must  be  imparted 
to  the  condenser,  i.  e.: 


Q  being  expressed  in  the  same  units  as  A.  Now  the 
cylinder  is  immersed  into  the  generator  or  boiler  and 
allowed  to  assume  the  temperature  T,,  while  the  volume 
remains  constant,  v2.  The  heat  which  is  hereby  con- 
veyed to  the  gas  is  — 

c(T,-T0) 

c  being  the  specific  heat  of  the  gas  at  constant  vol- 
ume. At  this  juncture  the  gas  is  allowed  to  expand  from 
the  volumeu2  to  the  volume  vt,  and  the  work  A±,  which 
is  done  on  the  piston,  is  expressed  by  — 

A,  = 


while  at  the  same  time  an  equivalent  amount  of  heat 
passes  from  the  generator  to  the  gas  in  the  cylinder,  i.  e.: 


Now  the  cylinder  is  brought  back  to  the  refrigerator, 
where,  while  the  volume  remains  constant,  the  temper- 
ature is  again  reduced  to  T0,  the  amount  of  heat, 
e(7\  —  T0),  being  transferred  from  the  gas  in  cylinder 
to  the  refrigerator  or  condenser.  The  gas  is  now  again 
in  its  initial  condition,  and  the  operations  for  one  period 
of  the  cycle  are  completed. 

The  useful  work,  W,  gained  by  this  operation  is— 


while  the  amount   of  heat,  H,  which    luis  been  with- 
drawn from  the  boiler  or  source  is  equal  to— 


THERMODYNAMICS.  69 

If  we  call  W  the  total  amount  of  work  gained,  and 
H  the  total  amount  of  heat  expended  by  the  heat  source 
to  obtain  the  heat  source,  we  can  write— 


H 


If  we  take  Tt— T0,  infinitesimally  small,  we  can  neg- 
lect the  term  c  (2\  —  T0)>  as  against  the  infinitely  greater 

quantity  E  T±  In  — — ,  and  we  can  write— 

V2 

W_  Tt  —  T0 
H~       T, 

EFFICIENCY  OF  IDEAL  CYCLE. 
W 

The  term  -n-,  i.  e..  the  work  obtained  divided  by  the 

_rz 

amount  of  heat  (expressed  in  the  same  units)  expresses 
what  is  termed  the  efficiency  of  the  cycle. 

Generally  speaking,  therefore,  the  convertibility  of  a 
certain  amount  of  heat  into  work  is  the  greater,  the 
greater  the  difference  of  temperature  between  boiler  and 
condenser,  i.  e.,  the  greater  T7,— T0,  and  the  lower  this 
difference  is  located  on  the  absolute  scale  of  temperature, 
that  is,  the  smaller  7\  under  otherwise  equal  conditions. 
The  limit  is  reached  when  T0  becomes  zero  (absolute)^ 
—493°  F.,  and  W  =  H,  a  condition  which  cannot  even  be 
approached  in  practical  working. 

CARNOT'S  IDEAL  CYCLE. 

The  ideal  cycle  originally  devised  by  Carnot  embraces 
four  such  operations.  First,  the  cylinder  with  piston  con- 
taining a  given  volume  of  a  permanent  gas  is  brought  in 
contact  with  the  heat  source  or  boiler,  and  after  it  has 
attained  that  temperature  and  the  pressure  correspond- 
ing thereto,  the  piston  is  allowed  to  move  forward 
against  a  resistance  which  is  continually  infinitesimally 
less  than  the  pressure  within  (i.  e.,  reversibly).  An 
amount  of  heat  equivalent  to  the  work  done  by  the  piston 
passes  from  the  source  of  heat  to  the  cylinder,  so  that  the 
gas  always  maintains  the  temperature  of  the  source, 
Aence  the  expansion  is  isothermal. 

Now  the  cylinder  is  removed  from  the  source  ot  heat 
to  conditions  which  are  supposed  to  be  so  that  it  cam 
neither  take  In  nor  give  out  heat,  and  while  under  such 


70  MECHANICAL  REFRIGERATION. 

conditions  the  piston  is  allowed  to  move  forward  again 
with  the  same  precaution  as  to  pressure.  The  expansion 
in  this  case  is  adiabatic,  and  it  is  allowed  to  proceed  until 
the  gas  in  the  cylinder  has  attained  the  temperature  of  the 
colder  body— the  refrigerator,  to  which  the  cylinder  is  then 
removed.  The  piston  is  now  forced  inward  reversibly, 
the  heat  of  compression  being  withdrawn  by  the  refrig- 
erator; the  temperature  remains  the  same, thus  constitut- 
ing an  isothermal  compression.  After  this  isothermal 
compression  the  cylinder  is  again  brought  under  condi- 
tions where  it  can  neither  absorb  nor  discharge  heat,  and 
under  these  conditions  is  further  compressed  reversibly, 
until  the  gas  within  has  acquired  the  temperature  of  the 
source  of  heat  or  boiler.  With  this  fourth  adiabatic 
operation,  the  cycle  is  completed,  the  working  substance 
having  been  returned  to  its  original  condition,  and  each 
and  all  operations  may  be  performed  in  the  re  versed  order. 

HEAT  ENGINES. 

A  heat  engine  is  a  contrivance  for  the  conversion  of 
heat  into  mechanical  energy,  and  in  accordance  with 
the  above  laws  the  efficiency  of  such  a  machine  does  not 
depend  on  the  nature  of  the  working  substance  (steam, 
hot  air,  exploding  gas  mixtures,  etc.),  but  only  on  the 
temperature  which  the  working  substance  has  when  ib 
enters  and  when  it  leaves  the  machine. 

AVAILABLE  EFFECT  OF  HEAT. 

The  relation  between  a  given  amount  of  heat  (H) 
employed  in  a  heat  engine  and  the  greatest  amount  of 
work  ( W)  which  can  be  derived  from  same  (expressed  in 
units  of  the  same  kind)  finds  its  expression  in  the  said 
equation: 

w 
'H 

in  which  Tt  is  the  temperature  at  which  the  heat  is  fur- 
nished to  the  engine,  and  T0  the  temperature  of  the  re- 
frigerator or  condenser  at  which  the  heat  leaves  the  en- 
gine. The  temperatures  are  expressed  in  degrees  of  ab- 
solute temperature. 

CONSEQUENCE  OF  SECOND  LAW. 

The  above  equation  is  a  concise  mathematical  ex- 
pression of  the  second  law  of  thermodynamics.  If  in  the 
same,  T0  becomes  zero  If  will  become  W;  in  other  words, 


THERMODYNAMICS.  71 

in  a  machine  in  which  the  refrigerator  or  condenser 
temperature  is  absolute  zero,  the  whole  amount  of  the 
heat  employed  can  be  converted  into  mechanical  energy, 
and  it  furnishes  an  important  additional  proof  for  the 
reality  of  an  absolute  zero  of  temperature,  which  is  fre- 
quently looked  upon  as  a  mere  scientific  fiction. 

IDEAL  REFRIGERATING  MACHINE. 

A  similar  deduction  can  be  made  when  the  opera- 
tions of  the  above  cycle  are  reversed,  the  gas  being  allowed 
to  expand  at  the  lower  temperature,  taking  heat  from  the 
refrigerator  and  its  compression  being  performed  at  the 
higher  temperature,  discharging  heat  into  the  boiler. 
Instead  of  heat  engine  we  have  now  a  refrigerating  ma- 
chine, and  one  representing  conditions  of  maximum 
efficiency  which  must  find  its  expression  in  the  same 
equation  reversed,  viz.: 

1L         yo 

w     Tt— rc 

EFFICIENCY  OF  REFRIGERATING  MACHINE. 

The  above  equation  signifies  that  by  expending  the 
amount  of  work  TT,  we  can  withdraw  the  amount  of 
heat  H  from  a  body  (refrigeration)  of  the  temperature 
T0,  and  transfer  the  same  to  a  body  (boiler  called  con- 
denser in  the  refrigerating  practice)  of  the  temperature 
2\.  The  equation  also  shows  that  the  efficiency  of  a 
refrigerating  engine  depends  on  conditions  quite  opposite 
to  those  applying  to  the  efficiency  of  a  heat  engine,  the 
conditions  being,  that  the  refrigeration  which  can  be 
obtained  by  expending  a  certain  amount  of  work  is  the 
greater  the  smaller  21!— T0,  and  the  larger  Tlf  that  is  the 
higher  Tt— T0  is  on  the  scale  of  temperature. 

FALL  OF  HEAT. 

In  analogy  with  the  conversion  of  the  energy  of 
falling  water  into  mechanical  energy  and  still  following 
Carnot,  it  is  sometimes  stated  that  the  amount  of  heat 
W  while  falling  from  the  temperature  Tt  to  T0  is  capable 
of  doing  the  work  H. 

We  see  now  that  this  expression  is  not  correct;  the 
amount  of  heat  W  leaves  the  source  or  boiler  haying  the 
temperature  Tt,  but  only  the  amount  TP— IT  enters  the 
refrigerator  or  falls  to  the  temperature  T0mm  reversible 
beat  engine. 


72  MECHANICAL  REFRIGERATION. 

On  the  other  band,  in  a  reversible  refrigerating  ma- 
chine the  amount  of  heat  W  leaves  the  refrigerator  at 
the  temperature  T0  and  the  amount  JF-j-  H  is  brought 
over  to  the  warmer  body  having  the  temperature  2\. 

COMPENSATED  TRANSFER  OF  HEAT. 

When  a  certain  amount  of  heat  passes  from  a  warmer 
to  a  colder  body  a  portion  of  the  same  can  be  intercepted, 
as  it  were,  to  be  converted  into  mechanical  energy  or 
work.  If  the  maximum  amount  of  work  obtainable  in  this 
manner  in  accordance  with  the  above  equation  has  beea 
produced,  the  transfer  of  heat  from  the  warmer  to  the 
colder  body  is  said  to  be  fully  compensated.  The  availa- 
bility of  the  energy  of  the  whole  system  participating  in 
the  transfer  has  not  been  changed,  since  the  process  is 
reversible  and  the  former  condition  can  be  fully  re-estab- 
iished,  theoretically  speaking. 

TJNCOMPENSATED  TRANSFER. 

When,  however,  heat  passes  from  a  warmer  to  a  colder 
body  without  doing  any  work  (as  is  the  case  in  radiation 
of  heat)  or  without  doing  the  maximum  amount  of  work 
obtainable,  a  corresponding  amount  of  the  availability 
of  energy  is  wasted  or  dissipated,  the  heat  at  the  lower 
temperature  being  lower  on  the  scale  of  availability  than 
it  was  before  the  transfer.  In  this  case  the  transfer  of 
heat  is  said  to  be  not  compensated,  or  only  partially  com- 
pensated. In  the  same  way  mechanical  energy  may  be 
dissipated  when  expended  without  transferring  the  max- 
imum amount  of  heat  from  a  colder  to  a  warmer  body,  as 
it  is  expected  to  do  in  the  refrigerating  practice. 

ENTROPY. 

This  term  is  used  to  convey  different  meanings  by 
different  writers.  It  was  originated  by  Clausius  to  stand 
for  a  mathematical  abstraction  expressing  the  degree  of 
non-availability  of  heat  energy  for  the  production  of  me- 
chanical energy  under  certain  conditions. 

LATENT  AND  FREE  ENERGY. 

That  portion  of  energy  present  in  a  system  which 
may  be  converted  into  its  equivalent  Of  mechanical  work 
is  called  free  energy,  and  the  remaining  energy  is  called 
latent  energy.  Hence  when  a  transfer  of  heat  takes 
place  in  a  system  without  due  compensation,  the  free 
energy  decreases,  and  the  latent  energy  of  the  system 


THERMODYNAMICS.  3 

increases  correspondingly.  In  accordance  with  this  con- 
ception the  latent  energy  of  a  body  divided  by  the  tem- 
perature is  the  entropy  of  the  body;  the  increase  of  the 
lament  energy  in  a  body,  divided  by  the  temperature  at 
which  it  takes  place,  yields  the  amount  of  increase  of  en- 
tropy, and  vice  versa. 

FUTURE  CONDITION  OF  UNIVERSE. 

Only  the  changes  of  the  entropy  can  be  determined, 
not  its  absolute  amount.  As  most  changes  take  place 
w  thout  full  compensation,  not  reversibly,  it  has  been 
ec  ncluded  that  the  entropy  of  the  universe  is  constantly 
increasing,  tending  toward  a  condition  when  all  energy 
will  be  latent,  i.e.,  not  available  for  further  conversion 
cr  changes.  In  reversible  changes  the  entropy  remains 
unchanged. 

CHANGES  OF  FREE  AND  LATENT  ENERGY. 

The  equation  expressing  the  efficiency  of  an  ideal 
ieversible  cycle  of  operations,  viz.: 

W_  T,-T0 
H~       Tt 

may  a?so  be  written— 


This  equation  furnishes  also  an  expression  for  the 
change  of  free  and  latent  energy  in  a  system  in  which 
transfer  of  heat  without  compensation,  or  with  only 
partial  compensation,  takes  place.  If  the  compensa- 

TT  I  fTI     _   /TT    \ 

tion  is  complete  the  expression  —  —  -^  --  &•  —  W  is 
sero,  and  the  amount  of  free  and  latent  energy  remains 

thesame;butifH(r^~To)  —  TF>0  that  is,  if  TFissmall- 
J-  1 

TT    /  /7T      _    rp     \ 

or  than   -'   l   ^  --  —  ,  the  equation  covers  all  cases  in 

which  the  changes  are  not  reversible,  and  the  con- 
version is  incomplete.  The  free  energy  of  the  sys- 
tem has  been  decreased  correspondingly  in  accordance 
with  this  equation.  As  W  can  never  become  larger 

ft  I  Ji     _  rp   \ 

than  -  —  ^  —  —  ,  the  above  difference  can  never  be  neg- 
ative, which  means  that  the  free  energy  of  a  system  can 


74  MECHANICAL  REFRIGERATION. 

never  increase.    If  in  the  equation,  W=     ^    *~       , 

J.  * 

—T0  is  equal  to  1,  the  equation  becomes— 


which  means  that  the  convertible  energy  of  the  amount 
of  heat,  J?,  while  passing  from  one  temperature  to  an- 
other one  degree  lower,  with  full  compensation,  is  equal 
to  that  amount  of  heat  divided  by  its  absolute  tempera- 
ture. 

INCREASE  OF  ENTROPY. 

If  an  amount  of  heat,  JT,  in  a  system  is  transferred 
from  a  higher  temperature,  T1}  to  a  lower  temperature, 
T0,without  compensation,  the  free  energy  decreases,  and 
the  latent  energy  increases  by  an  amount—? 


and  the  increase  of  entropy,  in  accordance  with  a  former 
definition,  is  expressed  by  the  term— 


Keversing  the  above  argument,  we  can  also  say:  If 
an  amount  of  heat,  H,  leaves  a  body  of  the  temperature 
T0  the  entropy  of  that  body  decreases  by  the  amount 

TT 

Tfrj  and  when  this  same  amount  of  heat  enters  another 
4  i 

body  of  the  temperature  T0  (transfer  without  compen- 
sation), the  entropy  of  the  second  body  is  increased  by  the 

Tf 

amount  -—  -.    The  increase  of  the  entropy  of  the  system 

-*o 

comprising  the  two  bodies  is  therefore,  as  above— 

H_        H_         -g(Tt-T0) 
TO        Tt   -          2\  T0   ' 

ORIGIN  OF  HEAT  ENERGY. 

The  source  of  nearly  all,  if  indeed  not  of  all,  forms  of 
energy  applicable  for  the  production  of  heat  and  power, 
is  traceable  to  the  sun,  the  radiant  energy  of  whose 
rays  has  been  converted  into  potential  or  chemical  energy 
in  the  plants,  whence  it  found  its  way  into  the  deposits 
of  coals,  etc.  The  heat  of  the  sun's  rays  also  produces 
the  vapors  which  reappear  as  water  falls,  etc.  ;  it  also  brings 


THERMODYNAMICS.  75 

about  the  commotion  in  the  atmosphere  which  appears 
in  the  force  of  waves  and  in  the  useful  applications  of 
the  wind  as  well  as  in  the  devastations  of  the  storm. 

SPECIFIC  HEAT  OF  GASES  AT  CONSTANT  VOLUME. 

In  accordance  with  the  molecular  theory,  the  specific 
heat  or  the  increase  of  heat  energy  for  an  increase  of  one 
degree  in  temperature  for  a  molecule  of  a  gas,  or  a  propor- 
tional quantity  of  the  same  of  the  weight,  Jf,  is  expres- 


in  which  CV  is  specific  molecular  heat  at  constant  volume, 
Tthe  absolute  temperature,  ./"the  mechanical  equivalent 
of  heat,  and  E  the  heat  required  to  increase  the  motion 
within  the  molecule,  u  the  velocity  of  the  molecule  as 
above  defined. 

SPECIFIC  HEATUOTER  CONSTANT  PRESSURE. 

If  a  gas  is  heated  under  constant  pressure  the  volume 
increases,  and  a  certain  amount  of  work  is  done,  the 
equivalent  of  which  in  heat  must  also  be  furnished  to  the 
gas  when  its  temperature  is  elevated.  If  we  express  the 
work  done  by— 

pv  __  I  Mu* 
T   =        8  T 

the  specific  heat  of  a  molecule  (expressed  in  units  of 
weight)  of  gas  under  constant  pressure,  Cp,  is— 

Mu* 


hence— 


IT  must  always  be  smaller  than  f  =  1.6667,  since  E  must 
always  be  positive,  and  when  it  is  very  small,  K  ap- 
proaches this  value,  as  for  vapor  of  mercury  (1.666),  in 
which  the  molecule  is  probably  composed  of  only  one 
atom,  while  in  gases  of  presumably  very  complex  mole- 
cules, the  value  for  K  approaches  the  other  limit,  viz.,  1, 
as  for  ether,  K=1.Q2Q. 

COMPONENTS  OF  SPECIFIC  HEAT  OF  GASES. 

From  the  foregoing  we  know  that  the  heat  required 
to  do  the  work  of  expansion,  when  a  gas  is  heated  under 


76  MECHANICAL  REFRIGERATION. 

constant  pressure,  is  always  equal  to  two-thirds  of  the 
heat  necessary  to  increase  the  energy  of  the  molecule.  We 
find  the  specific  heat,  ct,  for  equal  volumes  of  gases  under 
constant  pressure,  to  be  composed  as  follows: 

Heat  to  increase  molecular  motion =  3  x  0.034 

Heat  to  do  work  of  expansion =  2  x  0.034 

Heat  to  do  internal  work  (in  molecule)...  =n  x  0.034 

Specific  heat =  (n  -f  5)  0.034 

n  being  the  number  of  atoms  composing  the  molecule. 

As  for  perfect  gases,  we  can  substitute  equal  volumes 
for  equal  number  of  molecules  (since  the  same  volumes 
of  different  gases  contain  an  equal  number  of  molecules), 
we  can  also  say  that  for  equal  volumes  of  practically  per- 
fect gases,  the  specific  heat  is  the  same  (see  page  47). 

NEGATIVE  SPECIFIC  HEAT. 

When  the  heat  equivalent  of  the  work  required  to 
compress  a  saturated  vapor  from  a  lower  to  a  higher 
pressure  is  greater  than  the  heat  required  to  increase  the 
energy  of  the  molecules  of  that  vapor,  from  the  temper- 
ature corresponding  to  the  low  pressure  to  the  temper 
ature  corresponding  to  the  higher  pressure  of  the  satur- 
ated vapor,  then  the  specific  heat  of  such  saturated 
vapor  is  said  to  be  negative.  For  heat  must  be  abstracted 
during  compression  to  keep  it  in  a  saturated  condition, 
and  when  allowed  to  expand  a  portion  of  the  saturated 
vapor  will  condense  for  the  same  reason. 

AIR  THERMOMETER. 

As  the  expansion  of  liquids  and  solids  by  heat  is  not 
uniform  throughout  the  thermometric  scale,  this  con- 
stitutes a  serious  defect  in  all  thermometers  constructed 
by  their  aid.  This  difficulty  does  not  exist  when  air  or 
another  gaseous  body  is  used  as  the  thermometric  sub- 
stance. Hence  the  air  thermometer  is  used  for  exact 
determinations. 

THERMODYNAMIC   SCALE  OF  TEMPERATURE. 

If  a  thermometer  be  graduated  in  such  a  way  that 
each  degree  increase  in  temperature  of  the  thermometric 
substance  adds  equal  amounts  of  free  heat  energy  or 
equal  amounts  of  heat  available  for -mechanical  conver- 
sion to  the  thermometric  substance,  we  have  a  thermo- 
dynamic  scale  of  temperature  as  devised  by  Thomson. 
The  degrees  of  such  a  scale  agree  very  nearly  with  those 
of  the  air  thermometer. 


THERMODYNAMICS.  77 

HEAT  WEIGHT. 

In  accordance  with  the  terminology  adopted  by 
Zeuner,  the  "weight"  or  "heat  weight"  of  a  certain 
amount  of  heat,  H,  transferable  at  the  absolute  temper- 
ature T,  is  that  portion  or  fraction  of  said  amount  of 
heat  which  is  convertible  into  mechanical  energy,  viz.: 

-™-.    If  the  same  amount  of  heat,  H,  enters  a  body  at 

the  constant  absolute  temperature  T  (without  compen- 
sation), the  entropy  of  that  body  is  said  to  increase  by 

TT 

an  amount  -™-.    Hence  entropy  and  heat  weight  are  ex- 

jv/essions  which  are  numerically  synonymous.  The  terms 
thermodynamic  function  (Rankine),  and  Carnot's  func- 
tion are  used  in  the  same  connection.  Thomson's  ther- 
modynamic scale  of  temperature  shows  equal  heat  weights 
from  degree  to  degree. 

Thermodynamics  also  teaches  that  the  difference  be- 
tween the  specific  heat  of  a  gas  at  constant  pressure,  cp  , 
and  that  at  constant  volume,  cv,  is  a  constant  quantity, 
and  equal  to  the  constant  R  of  the  gas  equation,  viz.: 


ISENTROPIC  CHANGES. 

Adiabatic  changes  which  are  at  the  same  time  revers- 
ible are  also  called  isentropic  changes,  because  such 
changes  do  not  alter  the  entropy. 

LATENT  HEAT  AND  ENTROPY. 

The  heat  which  enters  a  body  at  the  same  or  at  con- 
stant temperature  is  called  latent  heat.  Hence  entropy 
may  also  be  defined  as  latent  heat  divided  by  the  corre- 
sponding temperature.  Accordingly  during  vaporization 
or  fusion  of  a  body  its  entropy  is  increased.  The  amount 
of  increase  may  be  expressed  by  -j~  when  I  stands  for  the 

latent  heat  of  vaporization  or  fusion,  and  T  for  the  boil- 
ing or  melting  point  expressed  in  absolute  degrees  F. 

If  a  gas  expands  at  constant  temperature  while  do- 
ing work,  it  absorbs  an  amount  of  heat  equivalent  to  the 
amount  of  work  done,  and  its  entropy  increases  corre- 
spondingly. Chemical  changes  taking  place  at  constant 
temperature  with  transferences  of  heat  cause  correspond- 
ing changes  of  entropy. 


78  MECHANICAL  REFRIGERATION. 

CHAPTER  VIII-MODERN  ENERGETICS 

INTRODUCTORY  REMARKS. 

In  the  foregoing  paragraphs  mass  has  been  treated 
as  one  of  the  fundamental  units,  and  as  the  vehicle  not 
only  of  mechanical  energy,  but  also  of  molecular  energy 
according  to  the  atomistic  or  mechanical  theory  of  natural 
phenomena,  which  is  still  more  or  less  generally  accepted, 
and  therefore  followed  in  this  compend. 

SYSTEM  OF  ENERGETICS. 

More  recently  following  the  example  of  Ostwald, 
Gibbs  and  others, it  has  been  found  expedient  to  consider 
energy  not  as  a  function  of  mass,  but  as  something  real, 
tangible  and  unchangeable  in  itself,  thus  creating  a  new 
series  of  scientific  conceptions  in  accordance  with  which 
mass  appears  in  the  role  of  a  factor  in  mechanical  energy. 

The  terminology  of  this  system  places  many  defini- 
tions in  a  plainer  and  clearer  light,  and  is  frequently 
used  in  discussions  on  questions  of  energy,  so  that  a 
synopsis  of  its  tenets  will  be  welcome  to  those  who 
desire  to  study  them. 

NEW  DEFINITION  OF  ENERGY. 

Energy  may  also  be  defined  as  that  immaterial 
quantity  which,  while  it  causes  the  greatest  variety  of 
changes  or  phenomena  between  different  objects,  always 
maintains  its  value.  This  definition  involves  the  princi- 
ple of  conservation  of  energy. 

CLASSIFICATION  OF  ENERGY. 

The  different  forms  of  energy  may  also  be  classified 
in  the  following  groups: 

1.  Mechanical  energy. 

2.  Heat. 

3.  Electric  and  magnetic  energy. 

4.  Chemical  or  internal  energy. 
6.    Radiated  energy. 

MECHANICAL  ENERGY. 

The  mechanical  energy  may  be  subdivided  into  two 
classes,  viz.: 

The  energy  of  motion  or  kinetic  energy,  and  the 
energy  of  space,  with  the  following  subdivisions: 

1.  Energy  of  distance  (force). 

2.  Energy  of  surface  (surface  tension). 
8.    Energy  of  volume  (pressure). 


MODERN  ENERGETICS.  79 

ENERGY   FACTORS. 

According  to  Helm,  etc.,  the  different  kinds  of  energy 
are  expressible  by  two  factors — one  of  intensity  and  the 
other  of  capacity.  -Equal  increases  or  decreases  of  energy 
in  a  given  system  or  configuration  of  bodies  correspond 
to  equal  increases  or  decreases  of  intensity,  or,  in  other 
words,  the  energy  of  a  system  is  proportional  to  its  in- 
tensity. This  may  be  expressed  by  the  formula 

in  which  E  represents  energy,  i  the  intensity  and  c  the 
factor  of  capacity  which  is  a  measure  for  the  amount  of 
energy  which  is  present  in  a  system  at  a  given  intensity, 
i,  the  latter  being  counted  from  E  =  0.  In  other  words, 
the  capacity  factor  for  energy,  c,  may  also  be  termed  the 
capacity  of  the  system  for  energy. 

The  capacity  and  intensity  factors  of  some  of  the 
various  forms  of  energy  are  given  as  follows: 

ENERGY.  CAPACITY.  INTENSITY. 

I  Mass  (m) .  Square  of  velocity  — 

A.  Kinetic  energy.  -{  v  9 

|  Quantity  of  motion  Velocity  — 
I  (mv).  2 

B.  Energies  of  space. 


a.    Energy  of 
distance, 
b.    Surface  en- 
ergy, 
c.    Energy  of 
volume. 
C.    Heat. 
D.    Electricity. 

E.    Magnetism. 
F.    Chemical  energy. 

Length. 

Surface. 

Volume. 
Capacity  for  heat. 
Quantity  of  elec- 
tricity. 
Quantity  of  mag- 
netism. 
Atomic  weight. 

Force. 

Surface  tension. 

Pressure. 
Temperature. 

Potential. 

Magnetic  potential. 
Affinity. 

DIMENSIONS  OF  ENERGY. 

The  definitions  of  the  conceptions  relating  to  energy, 
by  means  of  algebraical  expressions,  or  their  dimensions 
are  rendered  in  the  following  manner: 

If  e  stands  for  the  unit  of  energy,  t  for  time,  I  for 
length  or  distance  and  m  for  mass  the  dimensions  of  the 
different  mechanical  conceptions  may  be  expressed  as 
follows: 

OLD  UNITS.  NEW  UNITS. 

1.  Energy,  m  I2  t~*  e 

2.  Mass,  m  «r~»t* 

3.  Quantity  of  motion,  m  1 1    *  e  I — *  t 

4.  Force,  m  1 t~*  e  Z— » 

5.  Surface  tension,  _m  r~*  e  l~* 

6.  Pressure,  n  I    1  <~2  e  l~ » 

7.  Effect,  m  I2 t~3  e  «— * 


80  MECHANICAL  REFRIGERATION. 

The  first  three  definitions  belong  to  the  domain  of 
kinetic  energy,  4,  5  and  6  represent  potential  energies, 
and  7  the  effect  corresponding  to  the  mechanical  concep- 
tion of  a  horse  power. 

The  dimensions  as  given  in  the  second  column  differ 
from  those  in  the  first  column  in  that  the  third  funda- 
mental unit  energy  is  substituted  for  mass,  in  accord- 
ance with  the  foregoing  definition  of  energy  factors. 

THE   INTENSITY  PRINCIPLE. 

Energy  will  pass  from  places  of  higher  intensity  to 
such  of  lower  intensity;  but  energy  of  a  certain  intensity 
cannot  pass  to  such  of  the  same  or  of  higher  intensity.  A 
system  containing  but  one  kind  of  energy  is  in  equili- 
brium if  the  intensity  of  energy  is  the  same  throughout 
the  system.  If  the  intensity  is  not  the  same  changes 
will  occur  until  the  differences  in  intensity  have  be<!n 
equalized.  If  two  intensities  are  equal  to  a  third  intei- 
sity,  they  are  equal  among  themselves. 

COMPENSATION  OF  INTENSITIES. 

If  mere  than  one  kind  of  energy  is  present  in  a  sy?- 
tern  the  differences  in  intensity  of  one  kind  of  energy 
may  be  balanced  or  compensated  by  differences  in  the 
intensity  of  other  kinds  of  energy;  hence,  in  order  that  a 
change  may  take  place  in  such  a  system,  there  must  be 
differences  of  intensities  not  compensated. 

If  in  a  system  containing  several  forms  of  energy, 
there  are  sudden  leaps  or  differences  in  the  intensity  of 
one  energy  they  must  be  compensated  by  equivalent  sud- 
den leaps  or  differences  in  the  intensity  of  some  other  form 
of  energy  ia  order  that  equilibrium  may  exist  in  the 
system. 

REGULATIVE  PRINCIPLE  OF  ENERGY. 

Everything  that  happens,  every  change  or  phenome- 
non is  the  sensible  demonstration  of  a  transfer  or  trans- 
formation of  energy. 

Of  different  changes  possible  to  take  place  in  a  sys- 
tem containing  one  or  more  kinds  of  energy,  that  change 
will  take  place  which  causes  the  greatest  amount  of 
transformation  or  transference  of  energy  in  the  shortest 
time.  The  term  * '  possible  changes  "  implies  such  changes 
as  would  be  in  harmony  with  the  general  laws  of  energy. 

STATE   OF  EQUILIBRIUM. 

A  change  (compatible  with  the  conditions  of  exist- 
ence) in  a  system  containing  different  kinds  of  energy 


MODERN  ENERGETICS.  81 

in  equilibrium  must  add  and  abstract  equal  amounts  of 
energy  if  equilibrium  is  to  be  maintained.  The  algebra- 
ical sum  of  energy  lost  and  energy  gained  is  equal  to 
zero,  a  relation  providing  an  important  criterion  for  the 
state  of  equilibrium. 

ARTIFICIAL  AND  NATURAL  TRANSFER. 

Energy  may  maintain  equilibrium  or  become  trans- 
ferred or  transformed  artificially  by  means  of  certain  ap- 
pliances or  devices  (machines)  or  without  such  means. 
The  latter  transfers  may  be  called  natural  transfers. 

ARTIFICIAL  EQUILIBRIUM. 

If  in  a  system  containing  two  kinds  of  energy  in  equi- 
librium, the  compensation  of  the  intensities  is  effected  by 
artificial  means,  i.  c.,  a  machine,  then  such  a  contrivance 
directly  determines  the  relation  of  one  factor  of  one 
energy  to  one  factor  of  the  other  energy,  and  therefore 
indirectly  also  the  relation  of  the  other  factors. 

DISSIPATION  OF  ENERGY. 

The  difference  in  intensities  of  energy  not  compen- 
sated determines  the  ability  of  such  energy  to  do  work  or 
bring  about  changes.  Hence  the  difference  in  intensities 
is  a  measure  of  the  availability  of  the  respective  energy 
to  do  work.  After  a  change  has  taken  place  the  sum 
total  of  energy  (capacities  multiplied  by  intensities)  must 
be  the  same  as  before  the  change,  but  the  availability  of 
the  energy  for  the  production  of  further  changes  is  gener- 
ally lowered.  This  is  due  to  the  fact  that  after  the 
change  in  one  or  more  forms  of  energies  has  taken  place 
the  capacities  have  generally  been  increased  and  inten- 
sities decreased  correspondingly.  In  other  words,  the 
difference  in  the  intensity  of  one  energy  which  has  disap- 
peared has  not  been  compensated  by  the  appearance  of  an 
equivalent  difference  in  the  intensity  of  another  energy. 
The  tendency  which  prevails  in  all  natural  as  well  as 
artificial  processes  or  changes,  to  increase  the  capacity 
at  the  expense  of  the  intensity  of  existing  energy,  or,  in 
other  words,  to  obliterate  existing  differences  in  inten- 
sities, is  the  cause  of  what  is  termed  the  dissipation  of 
energy. 

RADIANT  ENERGY. 

The  state  or  condition  of  energy  while  on  its  way 
from  one  body  to  another  without  a  ponderable  inter- 
vening medium  is  called  "radiant  energy."  Energy  in 


32  MECHANICAL  REFRIGERATION. 

chis  condition  and  connection  is  supposed  to  possess  some 
of  the  qualities  referable  to  the  hypothetical  medium 
ether,  notably  elasticity. 

TRANSFORMATION  OF  ENERGY. 

The  compensation  of  a  change  in  one  form  of  energy 
by  an  equivalent  change  of  another  form  of  energy  con- 
stitutes what  is  also  termed  the  transformation  of  one 
kind  of  energy  into  another. 

BEVERSIBLE   CHANGES. 

If  the  change  produced  by  decreasing  the  difference 
in  intensity  of  a  given  quantity  of  one  form  of  energy 
has  been  fully  compensated  by  an  equivalent  amount  of 
difference  of  intensities  of  some  other  form  or  forms  of 
energies  having  made  its  appearance,  such  a  change  may 
be  considered  reversible  (in  the  abstract,  at  least).  Two 
co-ordinated  reversible  changes,  if  fully  performed,  re- 
establish the  original  condition  of  things  before  the 
change. 

IRREVERSIBLE    CHANGES. 

Changes  in  which  energy  is  dissipated  are  not  revers- 
ible, and  hence  may  be  termed  irreversible  changes. 

PERPETUAL  MOTION. 

Irreversible  changes  are  inseparably  connected  with 
all  practical  operations,  and  hence  a  perfectly  reversible 
operation  is  a  practical  impossibility.  Such  an  operation, 
if  it  were  possible,  could  be  repeated  without  end,  and 
would  constitute  what  is  termed  a  "conservative  system," 
which  would  be  a  kind  of  perpetual  motion  akin  to  that 
of  the  heavenly  bodies.  Such  a  perpetual  motion,  while 
beyond  the  possibilities  of  human  skill,  is  not  in  contra- 
diction with  the  laws  of  energy. 

Besides  the  perpetual  motion  of  a  conservative  sys- 
tem,wemake  a  distinction  between  attempts  at  perpetual 
motion  of  the  first  order  and  of  the  second  order. 

The  first  kind  contemplates  the  actual  creation  of 
energy,  or  of  power  to  do  work,  and  is  in  direct  conflict 
with  the  first  law  of  energy  proclaiming  its  absolute  con- 
servation and  indestructibility  and  its  transf  ormability  in 
equivalent  proportions. 

Perpetual  motion  of  the  second  order  involves  the 
elevation  of  the  intensity  of  energy  without  compensation, 
which  is  in  direct  conflict  with  the  intensity  principle  or 
the  second  law  of  energy. 


MODERN  ENERGETICS.  83 

CONTINUOUS  CONVERSION  OF  ENERGY. 

As  a  rule  nothing  could  be  gained  in  a  practical  way 
by  carrying  out  the  two  co-ordinate  systems  of  reversible 
changes;  the  useful  object  generally  is  to  produce 
changes  in  one  definite  direction,  and  not  undo  them  by 
reversion.  This  is  notably  the  case  in  our  efforts  to  con- 
vert energy  of  one  kind  into  energy  of  another  kind  by  a 
continuous  process,  as  when  heat  energy  is  converted 
into  motive  power  or  mechanical  energy,  etc. 

In  all  such  efforts  a  certain  percentage  of  energy  is 
dissipated,  that  is  the  energy  expended  cannot  all  be 
compensated  for  in  the  desired  direction. 

MAXIMUM  CONVERTIBILITY. 

It  follows  from  the  above  that  when  energy  is  trans- 
formed by  processes  or  operations  which  are  reversible  (in 
the  abstract,  at  least)  the  greatest  possible  amount  of 
transformation  (£.  e.,  incurring  no  dissipation  of  energy) 
is  effected,  as  otherwise  perpetual  motion  of  the  second 
order  could  be  produced  by  reversing  the  operations. 

For  the  same  reason  the  maximum  amount  of  energy 
obtainable  by  transforming  a  certain  amount  of  another 
energy  depends  solely  upon  the  uncompensated  difference 
in  the  intensity  of  the  latter  energy  and  on  the  position 
which  it  holds  on  an  absolute  intensity  scale,  counting 
intensity  from  its  proper  zero.  Hence  the  maximum  of 
transformation  obtainable  in  a  certain  direction  is  inde- 
pendent of  the  special  object  with  which  the  energy  is  con- 
nected, or  which  is  instrumental  in  the  transformation. 

INTENSITY  PRINCIPLE  AND  ENTROPY. 

The  intensity  principle  is  a  general  form  of  the  second 
law  of  thermodynamics.  It  broadly  asserts  that  while 
energy  of  any  kind  may  pass  from  places  of  higher  inten- 
sity to  such  of  lower  intensity  without  compensation, 
the  reverse  change,  i.  e.,  the  passage  of  energy  from 
places  of  lower  intensity  to  places  of  higher  intensity, 
can  never  take  place  without  compensation. 

In  all  natural  changes,  in  all  manifestations  of 
energy,  the  changes  are  either  so  as  to  fully  compensate 
each  other,  or  when  this  is  not  the  case,  the  deficiency  in 
compensation  must  correspond  to  so  much  increase  of 
latent  energy,  and  to  a  corresponding  increase  of  entropy. 
In  other  words,  natural  changes  proceed  either  without 
changing  the  entropy  or  by  increasing  the  same. 


84  MECHANICAL   REFRIGERATION. 

Hence  the  conception  of  the  entropy  function  enables 
us  to  determine  as  to  the  possibility  of  any  supposed 
change  in  a  system  of  bodies.  If  the  change  involves  a 
decrease  of  entropy,  it  must  be  deemed  impossible.  If, 
however,  the  change  involves  no  decrease  of  entropy,  but 
if  the  same  would  remain  unchanged  or  increase,  then 
the  said  change  is  not  in  conflict  with  the  laws  of  ener- 
getics. 

JUSTIFICATION  OF  CONCEPTS. 

The  importance  and  significance  of  the  above  some- 
what fragmentary  and  abstract  definitions  and  concepts 
becomes  more  apparent  in  the  treatment  of  the  different 
individual  branches  of  energetics,  and  especially  in  ther- 
modynamics. It  is  in  this  branch  that  the  above 
principles  have  their  origin  and  confirmation,  and  it  is  in 
this  branch  that  they  prove  their  adaptability  and 
usefulness  for  the  further  development  of  science,  which 
usefulness  must  plead  the  justification  of  these  concepts. 
Moreover  their  unrestricted  adaptability  in  all  other 
branches  of  science  appears  to  be  only  a  question  of  time. 

UNIFORM  UNITS  OF  ENERGY. 

One  kind  of  energy  being  transformable  into  an 
equivalent  amount  of  another,  it  is  indicated  to  so  select 
the  units  for  different  forms  of  energies  as  to  represent 
equivalent  quantities.  This  is  accomplished  in  a  manner 
by  some  of  the  C.  G.  S.  units. 

CHANGE  OF  ABSOLUTE  ZERO. 

In  the  foregoing  thermodynamic  discussions  the 
point  of  absolute  zero  has  been  taken  at  461  degrees  be- 
low zero  Fahrenheit,  as  it  is  universally  accepted  so  far. 
Recently,  however,  in  his  experiments  to  liquefy  helium 
(the  new  gaseous  element  discovered  in  the  atmosphere) 
Olszewski  reached  a  temperature  as  low  as  443°  below 
zero,  and  helium  remained  a  gas  still.  But  judging  from 
the  pressure,  etc.,  it  will  become  a  liquid  at  a  tempera- 
ture of  about  570°  F.  below  zero.  This  temperature 
must  therefore  still  be  above  absolute  zero,  although  it 
is  impossible  to  say  how  much.  At  any  rate,  it  is  more 
than  likely  that  a  different  absolute  zero  point  will  have 
to  be  accepted  in  the  future,  and  that  then  our  concep- 
tions in  thermodynamics  will  also  receive  important 
additions.  But  the  experiments  mentioned  must  be  fur- 
ther confirmed  before  any  definite  changes  are  advisable. 


MECHANICAL  REFRIGERATION. 


PART  II. 
PRACTICAL  APPLICATION. 


CHAPTER    I.-REFRIGERATION    IN  GENERAL. 

REFRIGERATION. 

The  act  of  reducing  the  temperature  of  any  body  or 
keeping  the  same  below  the  temperature  of  the  atmos- 
phere is  called  refrigeration. 

MEANS  OF   PRODUCING  REFRIGERATION. 

Refrigeration  may  be  produced  in  many  ways : 

1.  By  transferring  heat  from  a  warmer  body  to  a 
colder  one.    (Refrigeration  by  cooled  brine,  etc.) 

2.  By  the  consumption  of  heat  brought  about  by 
doing  work.    (Working  a  piston  against  resistance  with 
compressed  gas ;  air  machines.) 

.  3.    By  melting  or  dissolving  solid  bodies.    (Melting 
of  ice ;  solution  of  salts  in  water,  etc.) 

4.  By  evaporating  liquids  which  have  a  low  boiling 
point.  The  latent  heat  of  evaporation  represents  the 
amount  of  cold  that  can  be  produced  in  this  way. 
(Evaporating  liquid  ammonia,  liquid  carbonic  acid,  liquid 
sulphurous  acid,  ether,  etc.) 

AIR  MACHINES. 

The  mode  of  production  of  refrigeration  by  doing 
work  is  exemplified  in  the  air  machines,  as  that  of  Wind- 
hausen,  which  was  formerly  much  used  on  steamers  for 
refrigeration.  In  this  machine  the  atmospheric  air  13 
compressed  in  a  compressor,  the  heat  generated  by  com- 
pression being  carried  off  by  the  cooling  water.  The 
compressed  air  is  then  used  to  propel  an  engine,  whereby 
its  temperature  is  reduced  corresponding  to  the  work 
done  by  it  in  the  engine.  The  air  cooled  in  this  way  is 
then  introduced  into  the  rooms  to  be  refrigerated,  vent!- 


86  MECHANICAL  REFRIGERATION, 

lating  them  at  the  same  time.  The  machine  operates 
continuously,  but  the  refrigerating  agent  is  rejected 
along  with  the  heat  which  it  has  taken  up. 

FREEZING  MIXTURES. 

The  refrigeration  obtainable  by  dissolving  solid 
bodies  in  water  (freezing  mixtures)  has  been  referred  to 
on  pages  31  and  32.  This  method  may  alsp  be  employed 
in  a  continuous  process,  but  is  too  expensive  to  be  em- 
ployed on  a  large  scale,  and  when  done  so  is  chiefly  used 
as  an  expedient  when  other  means  fail.  In  such  case  a 
mixture  or  sol  ution  of  salt  in  ice  or  snow  is  generally  used. 

ICE   MACHINES. 

The  machines  which  are  now  used  for  the  pioduction 
of  refrigerating  effects  on  a  large  scale  are  nearly  all 
based  on  the  principle  of  production  of  cold  by  the 
evaporating  of  liquids.  Preference  is  given  to  either 
ammonia,  sulphurous  acid  or  carbonic  acid  as  the 
evaporating  liquid,  or  a  mixture  of  the  latter  two. 

CONSTRUCTION  OF  MACHINES. 

The  construction  of  the  machines  is  the  same  in 
principle,  no  matter  what  evaporating  liquid  is  employed, 
but  the  sizes  and  strength  of  different  parts  of  the  system 
vary  greatly  with  the  physical  properties  of  the  liquid, 
principally  the  latent  heat  of  evaporation,  the  tem- 
perature and  pressure  of  liquefaction,  etc. 

VAPORIZATION  MACHINES. 

The  machines  which  are  employed  to  practically 
utilize  the  heat  of  vaporization  for  refrigerating  purposes 
may  be  classified  as  vacuum  machines,  absorption  ma- 
chines, compression  machines,  and  mixed  absorption  and 
compression  machines. 

VACUUM   MACHINES. 

In  the  vacuum  machines  water  is  used  as  the  refrig- 
erating medium,  its  volatilization  at  a  temperature  suffi- 
ciently low  being  effected  by  means  of  vacuum  pumps,  the 
working  of  which  is  assisted  by  sulphuric  acid,  which 
absorbs  the  vapors  as  soon  as  formed,  thus  making  the 
action  of  the  vacuum  very  effective.  The  sulphuric  acid 
may  be  concentrated  for  repeated  use. 

ABSORPTION  MACHINES. 

The  absorption  machines  are  similar  to  the  vacuum 
machine  in  their  action,  the  difference  being  that  not 


REFRIGERATION  IN  GENERAL.  87 

water  but  a  liquid  (such  as  anhydrous  ammonia),  which 
evaporates  at  a  low  temperature  without  the  aid  of  a 
vacuum,  is  used  as  a  refrigerating  medium.  The  vapors, 
instead  of  being  absorbed  by  sulphuric  acid,  are  absorbed 
by  water,  and  from  this  they  are  separated  again  by  dis- 
tillation, and  liquefied  by  the  pressure  in  the  still  and  the 
aid  of  condensing  water. 

In  this  manner  all  the  larger  absorption  machines 
are  operated  continuously,  the  solution  of  ammonia  in 
water  being  subjected  to  distillation  in  a  still  heated  by 
a  steam  worm,  the  vapors  of  ammonia  entering  a  con- 
denser where  they  are  cooled  and  become  liquefied  into 
anhydrous  ammonia.  The  anhydrous  ammonia  is  kept 
in  a  liquid  receiver,  whence  it  enters  the  refrigerator  coils 
m  which  it  evaporates,  causing  a  refrigeration  corre- 
sponding to  its  heat  of  vaporization.  The  vapors  after 
having  done  this  duty  are  allowed  to  enter  the  absorber, 
where  they  come  in  contact  with  the  weak  solution  of 
ammonia  drawn  from  the  lower  portion  of  the  still,  and 
are  reabsorbed  by  the  same  with  generation  of  heat, 
which  is  carried  away  by  cooling  water.  The  rich  and 
cold  solution  of  ammonia  coming  from  the  absorber 
and  going  to  the  still,  and  the  poor  and  hot  solution  com- 
ing from  the  still  and  going  to  the  absorber,  are  passed 
through  a  device  called  the  exchanger  to  equalize  their 
temperatures  as  much  as  possible*  A  pump  is  required 
to  pump  the  rich  ammonia  solution  from  the  absorber 
into  the  still. 

THE  COMPRESSION  MACHINE. 

The  compression  machines  which  use  the  latent  heat 
of  vaporization  of  substances  having  a  low  boiling  point, 
puch  as  ammonia,  sulphurous  acid,  carbonic  acid,  etc., 
work  practically  all  on  the  same  principle.  The  vapors 
created  by  vaporization  of  the  refrigerating  medium  in  the 
lefrigerating  coils  enter  a  compression  pump,  which  is 
operated  by  a  steam  engine,  which  forces  the  vapor  into 
condenser  coils,  where  they  are  liquefied  with  the  aid  of 
cooling  water.  The  liquid  enters  a  liquid  receiver,  from 
which  it  is  allowed  to  enter  the  refrigerating  coils,  as  re- 
quired. The  process  is  continuous,  and  represents  a  cycle 
of  operations  as  the  working  substance  returns  period- 
ically to  its  original  state,  in  a  manner  which  approaches 
reversibility  more  or  less  according  to  the  modes  of  oper- 
ating the  different  machines, 


88  MECHANICAL  REFRIGERATION. 

AMMONIA  MACHINES. 

Owing  to  its  high  latent  heat  of  evaporation,  its 
comparatively  low  vapor  tension,  admitting  liquefaction 
at  a  comparatively  low  pressure  and  high  temperature, 
its  neutral  chemical  properties,  ammonia  is  highly  val- 
ued for  refrigerating  purposes,  and  ammonia  machines 
are  now  mostly  in  use  for  refrigerating  purposes  in  the 
United  States. 

PERFECT  COMPRESSION  SYSTEM. 

In  case  of  a  perfect  reversible  compression  system  the 
operations  would  have  to  consist  of  the  following  changes: 

First.— Evaporation  of  the  liquid  ammonia  at  the 
(constant)  temperature  of  the  refrigerator,  constituting 
an  isothermal  change. 

Second— Compression  of  the  vapor  so  formed  with- 
out addition  of  heat,  which  is  an  adiabatic  change. 

Third.— Condensation  of  the  compressed  vapor  at  the 
(constant)  temperature  of  the  condenser,  constituting 
another  isothermal  change. 

Fourth.— Reduction  of  the  temperature  of  the  liquid 
from  the  temperature  of  the  condenser  to  that  of  the 
refrigerator  by  means  of  vaporizing  a  portion  of  the 
liquid  and  doing  work  by  moving  a  piston.  This  is  the 
second  adiabatic  change,  and  it  returns  the  working  fluid 
to  its  initial  condition,  thus  completing  the  cycle. 

These  changes  are  conceived  to  be  carried  on  in  such 
a  manner  that  the  transfers  of  heat  follow  only  infini- 
tesimally  small  differences  in  temperature,  and  the 
changes  in  volume  take  place  under  but  inflnitesimally 
small  differences  of  pressure. 

REVERSIBLE    CYCLE. 

Under  these  circumstances  the  changes  can  also  be 
performed  in  the  opposite  direction,  and  therefore  the 
cycle  is  what  is  termed  a  reversible  cycle.  A  heat  engine 
as  well  as  a  refrigerating  apparatus  (a  heat  engine  re- 
versed), if  worked  on  the  plan  of  reversible  cycle,  is  work- 
ing on  the  most  economical  plan  that  can  be  conceived. 

For  this  reason  the  heat,  H,  removed  by  a  refrigerating 
apparatus  operated  strictly  on  this  basis  has  a  certain 
and  well  defined  relation  to  the  work  or  mechanical 
power,  TF,  required  to  lift  the  same  in  the  cycle  of  opera- 
tion. If  in  a  refrigerating  machine  so  operated  £t  is  the 
temperature  of  condenser  and  t0  the  temperature  of  the 
refrigerator  (Tl  and  TQ  designating  the  corresponding 


REFRIGERATION  IN  GENERAL. 


89 


absolute  temperatures)  thermodynamics  teaches  us  that 
the  following  relations  exist: 

Jfl_  _  t0  +  460  _       T0 
W  ~    tt-t0    ~  rl\—  T0 

DEFECT   IN  CYCLE. 

Thermodynamically  speaking,  there  should  be  no  dif- 
ference in  economy  on  account  of  the  nature  of  the  cir- 
culating fluid  if  a  perfect  cycle  of  operation  was  carried 
out,  but  practically  this  is  not  done.  In  all  compression 
machines  (barring  some  trials  in  the  case  of  carbonic  acid 
machines),  the  fourth  operation,  the  reduction  of  tem- 
perature of  the  liquid  while  doing  work,  is  not  carried 
out,  but  the  liquid  is  cooled  at  the  expense  of  the  refrig- 
eration of  the  system.  No  work  is  attempted,  as  the 
amount  obtainable  would  not  be  in  proportion  to  the  ex- 
pense involved  in  procuring  the  same.  This  defect  and 
other  conditions  in  the  working  of  a  reversible  cycle  have 
some  bearing  on  the  choice  of  the  circulating  medium. 

CHOICE  OF  CIRCULATING  MEDIUM. 

Iii  the  choice  of  a  circulating  medium,  therefore,  we 
should  consider  that  its  refrigerating  effect  depends  on 
the  latent  heat  of  vaporization  per  pound. 

That  the  size  of  the  compressor  depends  on  the  num- 
ber of  cubic  feet  of  vapor  that  must  be  taken  in  to  produce 
a  certain  amount  of  refrigeration,  and  the  strength  of  its 
parts  on  the  pressure  of  the  circulating  medium. 

And  also  that  the  loss  of  refrigeration  on  account  of 
cooling  the  liquid  circulating  medium  depends  on  the 
specific  heat  of  the  liquid  as  compared  with  the  heat  of 
volatilization. 

The  qualities  chiefly  involved  in  this  question  are 
compiled,  approximately,  in  the  following  table  for  the 
principal  liquids  employed  in  refrigeration. 


«S 

,Q  g 

|| 

£°s 

"o 

«| 

ISA 

£ 

=  2 

I*     |1| 

53 

<0    • 

11 

cS  ,, 

3  cn^ 
^1 

o'3 

-MCT  ' 

ej* 

^1^ 

0 

3 

ti. 

?g«2 

§3 

2  Co 

S  «- 

23 

2?^ 

r4 

Pbo 

2  s-s 

S3  O^ 

-  Sj^ 

i 

gsi 

i'S2«£: 

£ 

B^* 

> 

02 

a 

m 

Per  Ct. 

Sulphurous  acid 

10 

171  2 

7  35 

0  41 

23.3 

61  70 

0.24 

Carbonic  acid      .  . 

310 

123  2 

0  277 

1  00 

447. 

3  24 

0  81 

Ammonia  

30 

555.5 

9.10 

1.02 

61.7 

23.3 

0.18 

90  MECHANICAL  REFRIGERATION. 

This  table  explains  itself  and  readily  accounts  for 
the  preference  generally  given  to  ammonia  as  the  circu- 
lating fluid.  The  loss  due  to  the  cooling  of  the  liquid  as 
shown  in  percentage  for  every  degree  difference  in  tem- 
perature of  condenser  and  refrigerator,  is  less  than  in 
case  of  the  other  liquids,  and  the  total  refrigerating  effect 
per  pound  of  liquid  is  largest.  The  only  instance  speak- 
ing more  in  favor  of  sulphurous  acid  is  the  lower  press- 
ure of  its  vapor,  while  the  compressor  is  smallest  in  case 
of  carbonic  acid,  but  the  pressure  and  the  loss  due  to 
heating  of  liquid  is  very  large  in  the  latter  case. 

SIZE  OF  ICE  MACHINES. 

The  heat  unit;  as  already  stated,  is  used  for  measur- 
ing both  heating  and  refrigerating  effects.  As  a  matter 
of  convenience,  however,  the  capacity  of  large  refrig- 
erating plants  is  expressed  in  tons  of  ice.  By  a  ton  of 
refrigerating  capacity  used  in  the  above  connection 
is  meant  a  refrigerating  capacity  equivalent  to  a  ton  of 
ice  at  the  freezing  point  while  melting  into  water  at  the 
same  temperature.  This  refrigerating  capacity  is  equal 
to  284,000  units. 

ICE  MAKING  CAPACITY. 

The  refrigerating  capacity  of  a  machine  is  different 
from  the  actual  ice  making  capacity  of  a  plant;  the  lat- 
ter is  considerably  less,  fifty  per  cent  and  upward,  of  the 
refrigerating  capacity,  according  to  temperature  of  wa- 
ter, etc. 

USES  OF  REFRIGERATION. 

The  practical  uses  of  mechanical  refrigeration  are  so 
manifold  that  it  is  impossible  to  enumerate  them  all  in  a 
small  paragraph.  Foremost  among  them  is  cold  storage, 
that  is,  the  preservation  of  all  kinds  of  articles  of  food 
and  drink  by  the  application  of  low  temperature.  Slaugh- 
tering, packing  and  shipping  of  meat  can  hardly  be  car- 
ried on  nowadays  without  the  use  of  mechanical  refrig- 
eiation,  and  the  days  of  the  few  breweries  still  working 
without  this  artificial  appliance  may  be  said  to  be  num- 
bered. Since  ice  has  become  an  article  of  daily  necessity, 
there  are  few  towns  that  have  not  or  will  not  have 
their  artificial  ice  factory  or  factories. 

Artificial  refrigeration  is  or  will  be  used  for  a  great 
many  other  purposes,  some  of  which  will  be  mentioned 
later  on. 


PROPERTIES  OF  AMMONIA.  91 

CHAPTER  II.— PROPERTIES  OF  AMMONIA. 

FORMS  OF  AMMONIA. 

The  ammonia  occurs  in  practical  refrigeration  in 
thiee  different  forms,  as  the  liquid  anhydrous  ammonia, 
the  gaseous  anhydrous  ammonia  and  solutions  of  ammo- 
nia in  water  of  various  strengths. 

ANHYDROUS  AMMONIA. 

Ammonia  is  a  combination  of  nitrogen  and  hydrogen 
expressed  by  the  formula  NH3  which  means  that  an 
atom  of  nitrogen  (representing  14  parts  by  weight)  is 
combined  with  three  atoms  of  hydrogen  (representing 
fchree  parts  by  weight).  At  ordinary  temperatures  the  am- 
monia, or  anhydrous  ammonia,  as  it  is  called  in  its  nat- 
ural condition,  is  a  gas  or  vapor.  At  a  temperature  of 
—30°  F.  it  becomes  liquid  at  the  ordinary  pressure  of 
the  atmosphere,  and  at  higher  temperatures  also  if  higher 
pressures  are  employed.  The  anhydrous  ammonia  dis- 
solves in  water  in  different  proportions,  forming  what  is 
called  ammonia  water,  ammonia  liquor,  aqua  ammonia, 
otc.  At  a  temperature  of  900°  F.  ammonia  dissociates, 
>.hat  is,  it  is  decomposed  into  its  constituents,  nitrogen 
and  hydrogen,  the  latter  being  a  combustible  gas. 

It  appears  that  partial  decomposition  takes  place 
also  at  lower  temperatures,  but  probably  not  to  the  ex- 
tent frequently  supposed. 

The  liquid  ammonia  turns  into  a  solid  at  a  tempera- 
t  jre  of  about — 115°  F.  In  this  condition  it  is  heavier  than 
tje  liquid,  and  is  almost  without  smell.  At  a  tempera- 
tare  of  — 95°  F.  the  chemical  affinity  between  sulphuric 
acid  and  ammonia  is  zero,  no  reaction  taking  place  be- 
t  ;veen  the  two  substances  when  brought  in  contact  at  or 
below  this  temperature. 

Ammonia  is  not  combustible  at  the  ordinary  tem- 
perature, and  a  flame  is  extinguished  if  plunged  into  the 
gas.  But  if  ammonia  be  mixed  with  oxygen,  the  mixed 
gas  may  be  ignited  and  it  burns  with  a  pale  yellow  flame. 
Such  mixtures  may  be  termed  explosive  in  a  certain  sense. 

If  a  flame  sufficiently  hot  is  applied  to  a  jet  of  ammo- 
nia gas,  it  (or  rather,  the  hydrogen  of  the  same)  burns  as 
long  as  the  flame  is  applied,  furnishing  the  heat  required 
for  the  decomposition  of  the  ammonia. 

Ammonia  is  not  explosive,  but  when  in  drums  con- 
taining the  liquid  ammonia  not  sufficient  space  is  left  for 


92  MECHANICAL  REFRIGERATION. 

the  liquid  to  expand  when  subjected  to  a  higher  tempera- 
ture, the  drums  will  burst,  as  has  happened  frequently 
during  the  hot  season. 

The  ammonia  vapors  are  highly  suffocating,  and  for 
that  reason,  persons  engaged  in  rooms  charged  with  am- 
monia gas  must  protect  their  respiration  properly. 

PRESSURE  AND  TEMPERATURE  OF  AMMONIA. 

The  relation  between  pressure  and  temperature  of 
saturated  ammonia  vapor  is  expressed  by  the  formula : 

21  Qfi 

log.  10p  =  6.2495—  ! . 

T 

in  which  p  is  the  pressure  in  pounds  per  square  inch,  and 
T  the  absolute  temperature . 

DENSITY  OF  AMMONIA. 

The  density  d  of  liquid  anhydrous  ammonia  at 
different  temperatures,  water  being  1,  is  approxi- 
mately expressed  by  the  formula : 

(2  =  0.6502  —  0.00077  t, 
t  being  temperature  in  degrees  Fahrenheit. 

The  density  of  the  gas  is  0.597  at  32°  F.,  and  at  760 
mm.  pressure.  The  volume,  v,  of  the  saturated  vapor 
per  pound  may  be  calculated  by  the  formula : 

"  °  6.4993  p+"t  cubic  feet, 

in  which  P  is  the  pressure  in  pounds  per  square  foot,  T 
the  absolute  temperature,  h  the  latent  heat  of  vaporiza- 
tion. 

SPECIFIC  HEAT  OF   AMMONIA. 

The  specific  heat  of  liquefied  ammonia  is  variously 
stated  from  1  to  1.228.  The  specific  heat  of  ammonia 
gas  is  given  at  0.508  at  constant  pressure,  and  0.3913  at 
constant  volume.  The  coefficient  of  expansion  of  liquid 
ammonia  is  0.00204. 

The  specific  heat,  s,  of  saturated  vapor  of  ammonia 
is  expressed  by  the  formula: 

_  -,        555.5 

~^r 

This  value  is  negative  for  all  values  of  T  less  than 
555°  absolute,  which  means  that  if  saturated  ammonia 
vapor  is  expanded  adiabatically  a  portion  of  it  will  con- 
dense, giving  up  its  heat  to  the  remainder  of  the  vapor, 


PROPERTIES  OP  AMMONIA.  93 

thus  maintaining  the  temperature  corresponding  to  the 
pressure  of  saturation,  and  when  compressed  heat  must  be 
abstracted,  if  the  temperature  and  pressure  are  continu- 
ally to  correspond  .to  those  of  the  state  of  saturation, 
otherwise  it  will  become  superheated. 

SPECIFIC  VOLUME  OF  LIQUID. 

The  specific  volume,  v±1  of  liquefied  ammonia  may  be 
found  after  the  following  rule: 

Cubicfeet- 
LATENT  HEAT. 

The  latent  heat,  h,  of  evaporation  of  ammonia  is 

h  =  555.5  —  0.613  1  —  0.000219  «2, 
in  which  formula  t  stands  for  degrees  F. 

EXTERNAL  HEAT. 

That  portion  of  the  latent  hpat  required  to  overcome 
external  pressure  or  the  external  latent  heat,  E,  is  ex- 
pressed by  — 


J 

in  which  formula  P  stands  for  external  pressure  in 
pounds  per  square  foot,  v  for  the  volume  of  the  vapor, 
and  vt  for  the  volume  of  the  liquid  (which  is  neglected  in 
the  calculations  given  in  the  accompanying  table),  and  J 
the  mechanical  equivalent  of  heat. 

•WEIGHT  OF  AMMONIA. 

The  weight,  w,  of  a  cubic  foot  of  the  saturated  vapor 

is-  1 

w  =  —  • 

V 

And  the  weight,  wlt  of  a  cubic  foot  of  the  liquid  is— 


The  weight  of  one  cubic  foot  of  liquid  ammonia  at  a 
temperature  of  32°  F.  is  39.017  pounds. 

TABULATED  PROPERTIES  OF   SATURATED  AMMONIA. 

The  physical  properties  of  anhydrous  ammonia,  both 
in  the  vapor  and  liquid  state,  which  are  of  special  use 
in  the  refrigerating  practice,  are  laid  down  in  the  follow- 
ing table  prepared  by  De  Volson  Wood,  calculated  by 
the  above  formulae  which  have  been  elaborated  by  him 
also. 


94 


MECHANICAL  REFBIGERATION. 


PROPERTIES  OF  SATURATED  AMMONIA. 


TEMPERA- 
TURE. 

PRESSURE, 
ABSOLUTE. 

!_, 

B 

External  Heat. 
Thermal  Units. 

Internal  Heat,  Ther- 
mal Units. 

fs 

£ 

^ 

"o  r 

it 

II 

fa 

Absolute. 

£ 

5 

6* 

GO 

? 

—  40 
—  35 
—  30 

420.66 
425.66 
430.66 

1540.9 
1773.6 
2035.8 

10.69 
12.31 
14.13 

579.67 
576.69 
573.69 

48.23 

48.48 
48.77 

531.44 
628.21 
524.92 

24.37 
21.29 
18.66 

.0234 
.0236 
.0237 

.0410 
.0467 
.0535 

—  25 
—  20 
—  15 

435.66 
440.66 
445.66 

2329.5 
2657.5 
3022.6 

16.17 
18.45 
20.99 

570.68 
667.67 
564.64 

49.06 
49.38 
49.67 

521.62 

518.29 
514.97 

16.41 

14.48 
12.81 

.0*38 
.0240 
.0242 

.0609 
.0690 
.0779 

—  10 
—    6 
0 

450.66 
455.66 
460.66 

3428.0 

3877.2 
4373.5 

23.77 
26.93 
30.37 

561.61 
658.56 
555.50 

49.99 
50.31 
50.68 

511.62 

508.25 
504.82 

11.36 
10.12 
9.04 

.0243 
.0244 

.oaie 

.0878 
.0988 
.1109 

+    6 

T  10 
+  15 

465.66 
470.66 
475.66 

4920.5 
5522.2 
6182.4 

34.17 
38.65 
42.93 

552.43 
549.35 
646.26 

60.84 
51.13 
51.33 

601.69 

498.22 
494.93 

8.06 
7.23 
6.49 

!0249 
.0250 

.1241 
.1384 
.1540 

+  20 

+  25 
+  30 

480.66 
485.66 
490.66 

6905.3 
7695.2 
8566.6 

47.96 
53.43 
59.41 

543.15 
540.03 
536.92 

51.61 

61.80 
52.01 

491.54 
488.23 
484.91 

5.84 
5.26 
4.75 

.0252 
.025:5 
.0254 

.1712 

.1901 
.2105 

+  35 

It§ 

495.66 
600.66 
506.66 

9493.9 
10512 
11616 

65.93 
73.00 
80.66 

533.78 
530.63 
527.47 

52.22 
52.42 
52.62 

481.56 
478.21 
474.  85 

4.31 
3.91 
3.56 

.0256 
.0257 
.0260 

.2320 
.2583 
.2809 

+  50 
+  55 
+  60 

510.66 
515.66 
620.66 

12811 
14102 
15494 

88.96 
97.93 
107.60 

524.30 
521.12 
517.  93 

52.82 
53.01 
53.21 

471.48 
468.11 
464.72 

3.25 
2.96 
2.70 

.0260 
.0260 
.0265 

.3109 
.33,9 
.3704 

+  66 
+  70 

+  75 

525.66 
530.66 
536.66 

16993 
18605 
20336 

118.03 
129.21 
141.25 

514.73 
511.52 

508.29 

53.38 
53.57 
53.76 

461.35 
457.85 
464.63 

2.48 

2.27 
2.08 

.0266 
.0268 
.0270 

.4034 
.4405 

.4808 

+  80 
+  85 
+  90 

540.66 
545.66 
550.66 

22192 
24178 
26300 

154.11 

167.86 
182.8 

504.66 
501.81 
498.11 

53.96 
54.15 

54.28 

450.70 
447.66 
443.83 

.91 

.77 
.64 

.0272 
.0273 
.0274 

.5262 
.5649 
.6098 

+  90 
+  100 
+  105 

555.66 
560.66 
565.66 

28565 
30980 
33660 

198.37 
215.14 
232.98 

495.29 
491.50 

488.72 

54.41 
54.54 
54.67 

440.83 
436.96 
434.08 

.51 
.39 

.289 

.0277 
.0279 
.0281 

.6622 
.7194 
.7757 

JUO 
115 
120 

570.66 
675.66 
580.66 

36284 
39188 
42267 

251.97 
272.14 
293.49 

485.42 
482.41 

478.79 

54.78 
54.91 
55.03 

430.64 
427.40 
423.75 

.203 
.121 
1.041 

.0283 
.0285 

.0287 

.8312 
.8912 
.9608 

+  126 

+  130 
+  135 

585.66 
590.66 
595.66 

45528 
48978 
52626 

316.16 

340.42 
365.16 

475.45 
472.11 
468.75 

55.09 
55.16 
55.22 

420.39 
416.94 
413.53 

.9699 
.9051 

.8457 

.0289 
.0291 
.0293 

1.0310 
1  1048 
1.1824 

+  140 
+  145 
+  160 

600.66 
605.66 
610.66 

66483 
60550 
64833 

392.22 
420.49 
460.20 

465.39 
462.01 
458.62 

55.29 
65.34 
56.39 

410.09 
406.67 
402.23 

.7910 

.7408 
.6946 

.0295 
.0297 
.0299 

1.2642 
1.3497 
1.4396 

+  165 
+  160 
+  165 

615.66 
620.66 
625.66 

69341 
74086 
79071 

481.54 
614.40 
549.04 

455.22 
451.81 
448.39 

55.43 
65.46 
55.48 

399.79 
396.35 
392.94 

.6511 
.6128 
.5765 

.0302 
.0304 
.0306 

1.5358 
1.6318 
1.7344 

The  critical  pressure  of  ammonia  is  115  atmospheres,  the  critical 
temperature  at26«oF.  (Dewar),  critical  volume  .00482  (calculated). 


PROPERTIES  OF  AMMONIA.  95 

VAN  DEB  WAALS'  FORMULA  FOR  AMMONIA. 

As  has  been  shown  (page  56),  the  constants  a  and 
b  of  Van  der  .Waals'  formula  can  be  derived  from  the 
critical  data,  which  gave  me  the  following  values  for  am- 

monia : 

a  =  .0079;  &  =  .0016. 

If  the  values  for  a  and  b  thus  found  for  ammonia  are 
introduced  in  the  general  equation  (page  56),  setting  p0 
and  v0  equal  unit,  the  equation  will  read  : 

(«-0.0018)=(l  +  . 

0.0079  )  1.00627  X  (461  + 

or 


This  equation  may  be  used  to  establish  the  relations 
between  pressure,  volume  and  temperature  for  anhydrous 
ammonia,  and  in  order  to  test  the  same  we  may  compare 
the  results  so  obtained  with  those  derived  from  actual  ex- 
periments for  saturated  ammonia  vapor,  the  volume  of 
which  ought  to  satisfy  one  of  the  three  values  for  v 
which  are  possible  below  the  critical  temperature  at  the 
pressure  of  liquefaction. 

On  this  basis  the  values,  pt,  for  the  pressure  of  am- 
monia gas  for  given  volumes  at  given  temperatures  have 
been  calculated  in  the  following  table: 

t  p  v         VI=T?       Pt 

—  40              0.71  24,37  1.282               0.66 

—  15              1.38  12.81  0-674                1.33 
+  32              3.96  4.57  0.24                 4.02 
+  60              7.17  2.7  0.142                7.24 
+122  20.3  1.0  0.052  20.4 
+165  36.6  0.57  0.030  36.4 

In  this  table  the  values  forp  and  i^  for  the  tempera- 
ture t  are  in  accordance  with  Wood's  interpretation  of 
Regnault's  experiments  for  saturated  ammonia  vapor, 
and  the  values,  plt  are  derived  from  the  above  formula 
for  ammonia  by  inserting  the  value,  wt,  obtained  in 
measuring  the  volume  by  the  volume  of.  an  equal  weight 
of  ammonia  gas  at  the  pressure  of  one  atmosphere  at  32° 
F.  It  will  be  noticed  that  pt  agrees  pretty  closely  with 
p  between  —  15°  and  165°,  thus  proving  the  approximate 
correctness  of  Waals'  formula  for  saturated  ammonia 
within  these  temperatures,  and  therefore  the  formula 
may  doubtless  also  be  safely  used  for  superheated  vapor 
of  this  substance  within  these  limits  for  approximate 


96  MECHANICAL   REFRIGERATION. 

estimation.  Indeed,  the  agreement  between  the  two  sets 
of  pressures  obtained  by  entirely  different  experiments, 
and  by  an  entirely  different  course  of  reasoning,  is  suffi- 
ciently close  to  inspire  the  greatest  confidence  in  the  ex- 
periments of  Regnault  and  Dewar,  as  well  as  in  the 
mathematical  deductions  of  Van  der  Waals. 

SUPERHEATED  AMMONIA  VAPOR. 

Below  its  critical  temperature  (130°  F.)  ammonia  in 
its  volatile  condition  is  to  be  termed  a  vapor,  strictly 
speaking;  but  when  it  is  not  in  a  saturated  condition,  but 
in  the  condition  of  a  superheated  vapor,  as  it  were,  it  be- 
haves practically  like  a  permanent  gas  and  is  also  termed 
ammonia  gas.  In  this  condition  one  pound  of  ammonia 
gas,  under  a  pressure  of  an  atmosphere,  and  at  the  tem- 
perature of  32°  F.  occupies  a  volume  of  20.7  cubic  feet 
(one  cubic  foot  of  air  weighing  0.0806  pound,  and  the 
specific  gravity  of  ammonia  being  0.597  of  air  under  these 
conditions). 

FORMULAE  FOR  SUPERHEATED  VAPOR. 

On  this  basis  the  relations  of  volume,  weight,  press- 
ure and  temperature  of  ammonia  gas  or  superheated  am- 
monia vapor  can  be  calculated  after  the  general  equation 
of  gases  on  pages  46  and  51. 

The  volume  v  in  cubic  feet  of  one  pound  of  ammonia 
gas  at  any  temperature,  £,  and  for  any  pressure,  p,  expressed 
in  pounds  per  square  inch  below  that  which  corresponds  to 
the  pressure  of  saturated  vapor  at  that  temperature,  or 
for  any  pressure  and  for  any  temperature  above  that 
which  corresponds  to  the  temperature  of  saturated  vapor 
at  that  pressure,  can  be  found  approximately  after  the 
formula— 

20.7  (461  -f 1)  14.7      20.7  (461  -f  t)       0  62  (461  -f  t) 
493  X  p  33.5  p  p 

If  the  volume,  u,  in  cubic  feet  of  one  pound  of  am- 
monia gas  at  a  certain  temperature,  i,  is  known,  the  press- 
ure can  be  found  after  the  equation — 

_  20.7(461'+*)       0.62(461  +t) 
P  =         33.5  v  v 

And  if  the  volume,  v,  and  the  pressure,  p,  are  known  the 
temperature  may  be  determined  approximately  after  the 
equation— 

t  =  1.62   >  v  —  461 


PROPERTIES  OF  AMMONIA. 


97 


As  stated  above,  the  formula  of  Van  der  Waals  may 
also  be  used  in  this  connection,  but  it  is  rather  too  cumber- 
some for  this  purpose.  However,  if  the  value  of  20.7  in 
the  foregoing  formulae  is  substituted  by  19,  which  is  the 
figure  found  in  accordance  with  Van  der  Waals'  equation, 
the  results  agree  closer  with  the  figures  obtaining  for 
vapor  just  saturated.  The  table  on  "  Properties  of  Am- 
monia Gas  or  Superheated  Vapor  of  Ammonia  "  in  the 
appendix  agrees  practically  with  the  formula  given  forv, 
on  page  96,  and  for  this  reason  gives  only  approximate 
values,  since  said  formula  considers  ammonia  a  perfect 
gas,  which  it  is  not,  as  indicated  by  Van  der  Waals. 

AMMONIA  LIQUOR. 

The  solutions  of  anhydrous  ammonia  in  water  are 
employed  in  the  so  called  absorption  machines,  and  the 
properties  of  such  solutions  vary  with  their  strength  or 
the  percentage  of  ammonia  which  they  contain.  The 
strength  of  such  solutions, "ammonia  liquor,"  as  they  are 
commonly  called,  is  approximately  determined  by  spe- 
cific gravity  scales  or  hydrometers,  those  of  Beaume  be- 
ing usually  employed  for  this  purpose. 

STRENGTH  OF  AMMONIA  LIQUOR. 


Percentage  of 
Ammonia 
by  Weight. 

Specific 
Gravity. 

Degrees 
Beaume 
Water  10. 

Degrees 
Beauine" 
Water  0. 

0 

1.000 

10 

0 

1 

0.993 

11 

1 

2 

0.986 

12 

2 

4 

0.979 

13 

3 

6 

0.972 

14 

4 

8 

0.966 

15 

5 

10 

0.960 

16 

6 

12 

0.953 

17.1 

7 

14 

0.945 

18.3 

8.2 

16 

0.938 

19.5 

9.2 

18 

0.931 

20.7 

10.3 

20 

0.925 

21.7 

11.2 

22 

0.919 

22.8 

12.3 

24 

0.913 

23.9 

J3.2 

26 

0.907 

24.8 

14.3 

28 

0.902 

25.7 

15.2 

30 

0.897 

26.6 

16.2 

32 

O.H92 

27.5 

17.3 

34 

0.888 

28.4 

18.2 

36 

29.3 

19.1 

38 

0.8BO 

30.2 

20.0 

PROPERTIES  OF  AMMONIA  LIQUOR. 

On  the  following  pages  we  publish  a  table  prepared 
by  Starr,  and  based  on  experiments  made  by  him,  which 
shows  the  relations  between  pressure  and  temperature 
for  solutions  of  ammonia  in  water  of  different  strengths. 


MECHANICAL  REFKIGEBATION. 


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MECHANICAL  REFRIGERATION. 
BEAUME  SCALES. 


It  should  be  noted  that  there  are  three  BeaumS  spe- 
cific gravity  scales,  or  hydrometers;  one  of  liquids  which 
are  heavier  than  water,  and  two  for  liquids  lighter  than 
water.  Of  the  latter  two  the  scale  of  the  one  designates 
pure  water  10,  and  the  other  designates  pure  water  zero. 
As  ammonia  liquor  (comprising  mixtures  of  water  and 
ammonia  in  all  proportions)  is  lighter  than  water,  only 
the  latter  two  Beaume  scales  come  into  question  in  this 
respect,  and  generally  the  one  which  designates  pure 
water  10  is  referred  to  when  mentioned  in  connection 
with  ammonia  liquor,  and  the  degrees  given  in  this  con- 
nection correspond  to  a  certain  specific  gravity,  i.  e.,  to  a 
certain  percentage  of  water  and  ammonia  contained  in 
the  ammonia  liquor  as  shown  in  the  table  on  page  97, 

SATURATED  SOLUTION  OF  AMMONIA. 

The  amount  of  ammonia  which  can  be  absorbed  by 
water  decreases  with  the  temperature,  as  is  shown  in  the 
following  table. 

SOLUBILITY    OF    AMMONIA     IN    WATER    AT    DIFFERENT 
TEMPERATURES  (ROSCOE). 


Pounds  of 

Pounds  of 

Degrees 
Celsius. 

Degrees 
Fahrenheit. 

NH3  to  one 
pound 

Degrees 
Celsius. 

Degrees 
Fahrenheit. 

NH3  to  on* 
pound 

water. 

water. 

0 

32. 

"*'    0.875 

28 

83.4 

0.426 

3 

4 

35.6 
39.2 

0.833 
0.792 

30 
32 

86. 
89.6 

0.403 
0.382 

6 

42.8 

0.751 

34 

93.2 

0.362 

8 

46.4 

0.713 

36 

96.8 

0.343 

10 

50. 

0.679 

38 

100.4 

0.324 

12 

63.6 

0.645 

40 

104.0 

0.307 

14 

57.2 

0.612 

42 

107.6    . 

0.290 

16 

60.8 

0.582 

44 

111.2 

0.276 

18 

64.4 

0.554 

46 

114.8 

0.259 

20 

68. 

0.526 

48 

118.4 

0.244 

22 

71.6 

0.499 

60 

122. 

0.229 

24 

75.2 

0.474 

52 

125.6 

0.214 

26 

78.8 

0.449 

54 

129.2 

0.200 

56 

132.8 

0.18G 

The  heat  Hn  developed  when  one  pound  of  ammonia 
is  dissolved  in  as  much  poor  liquor  containing  one  pound 
of  ammonia  to  n  pound  of  water,  in  order  to  obtain  a 
rich  liquor  which  will  contain  6  +  1  pound  of  ammonia 
for  each  n  pound  of  water  (see  pages  99  and  100)  is — 
284  +  1426 
n 


Hn  =  925  — 


units. 


PROPERTIES  OF  AMMONIA. 


101 


The  figures  in  the  following  table  on  the  solubility 
of  ammonia  in  water  at  different  temperatures  have  been 
obtained  by  Sims: 


Degrees 
Fahr. 

Lb.ofNH8 
to  lib. 
of  Water. 

Volume  of 
NH8  in  1 
Volume  of 
Water. 

Degrees 
Fahr. 

Lb.ofNH8 
to  1  Ib. 
of  Water. 

Volume  of 
NHsinl 
Volume  of 
Water. 

32.0 

0.899 

1,180 

125.6 

0.274 

359 

35.6 

0.853 

1,120 

129.8 

0.265 

348 

39.2 

0.809 

1,062 

133.8 

0.256 

336 

42.8 

0.765 

1,005 

136.4 

0.247 

324 

46.4 

0.724 

951 

140.0 

0.238 

312 

50.0 

0.684 

898 

143.6 

0.229 

301 

53.6 

0.646 

848 

147.2 

0.2?0 

289 

67.2 

0.611 

802 

150.8 

0.211 

277 

60.8 

0.578 

759 

154.4 

0.202 

265 

64.4 

0.546 

717 

158.0 

0.194 

254 

68.0 

0.518 

683 

161.6 

0.186 

244 

71.6 

0.490 

643 

165.2 

0.178 

234 

75.  2 

0.4G7 

613 

168.8 

0.170 

223 

78.8 

0.446 

585 

172.4 

0.162 

218 

82.4 

0.426 

559 

176.0 

0.154 

202 

86.0 

0.408 

536 

179.6 

0.146 

192 

89.2 

0.393 

516 

183.2 

0.138 

181 

93.2 

0.378 

496 

186.8 

0.130 

170 

96.8 

478 

190.4 

0.122 

160 

100.4 

0  350 

459 

194.0 

0.114 

149 

1U4.0 

0'.338 

444 

197.6 

0.106 

139 

107.6 

0.326 

428 

201.2 

0.098 

128 

111.2 

0.315 

414 

204.8 

0.090 

118 

114.8 

0.303 

399 

208.4 

0.082 

107 

118.4 

0.294 

386 

212.0 

0.074 

97 

122.0 

0.284 

373 

HEAT  GENERATED  BY  ABSORPTION  OF  AMMONIA. 

The  questions  regarding  the  heat  generated  by  the 
absorption  of  ammonia  in  water,  as  well  as  in  water  con- 
taining a  certain  percentage  of  ammonia,  have  been  ex- 
perimentally studied  by  Berthelot,  whose  results  may  bo 
expressed  by  the  following  formula : 

/->     142 
O  =  —  units. 
n 

in  which  Q  stands  for  the  units  of  heat  (pound  Fahren- 
heit) developed  when  a  solution  containing  one  pound 
of  ammonia  in  n  pounds  of  water  is  diluted  with  a  great 
amount  of  water.  This  equation  fully  suffices  to  solve 
the  different  problems  arising  in  refrigerating  prac- 
tice. Assuming  925  units  (the  values  of  different  ex- 
perimenters differ)  of  heat  to  be  developed  when  one 
pound  of  ammonia  is  absorbed  by  a  great  deal  (say  200 
pounds)  of  water,  the  amount  of  heat,  Q,  developed  in 
making  solutions  of  different  strengths  (one  pound  of 
ammonia  to  n  pounds  of  water)  may  be  expressed  by 
tbe  formula-  ^  =  925  __  142 


102 


MECHANICAL  REFRIGERATION. 


The  heat,  §2,  developed  when  6  pounds  of  ammonia 
are  added  to  a  solution  containing  one  pound  of  am- 
monia to  n  pounds  of  water,  is  expressible  by  the 
formula :  i  A 


Let  the  poor  liquor  enter  the  absorber  with  a  strength 
of  10  per  cent,  which  is  equal  to  one  pound  of  ammonia 
to  nine  (n)  pounds  of  water.  Let  the  rich  liquor  leave 
the  absorber  with  a  strength  of  25  per  cent,  which  is 
three  (i+&)  pounds  of  ammonia  per  nine  (n)  pounds  of 
water.  Inserting  these  values,  n  =  9  and  6  =  2,  in  the 
above  equation,  we  have— 


142(4+4) 
9 


1724  units. 


Hence  by  dissolving  two  pounds  of  ammonia  gas  or 
vapor  in  a  solution  of  one  pound  of  ammonia  in  nire 
pounds  of  water,  we  obtain  twelve  pounds  of  a  25  percent 
solution,  and  the  heat  generated  is  1,724  B.  T.  units. 

SOLUBILITY  OF  AMMONIA  IN  WATER  AT  DIFFERENT  TEM- 
PERATURES AND  PRESSURES.      (SIMS.) 

One  Pound  of  Water  (also  Unit  Volume],  Absorbs  the  Following  Quan- 
tities of  Ammonia. 


Absolute 
Pr's'ure  in 
Lbs.  per 
Sq.  Inch. 

32° 
Lbs. 

P. 

Vols. 

68°  F. 

104°  F. 

212°  F. 

Lbs. 

Vols. 

Lbs. 

Vols. 

Gr'ms. 

Vol 

14.67 

0.899 

.IbO 

0.618 

.683 

0.338 

.443 

0.074 

.97 

15.44 

0.937 

,5531 

0.635 

.703 

0.349 

.458 

0.078 

.102 

16.41 

0.980 

.287 

0.566 

.730 

0.363 

.476 

0.083 

.109 

IV.  37 

.02it 

.351 

0.574 

.754 

0.378 

496 

0.088 

.115 

18.34 

.077 

.414 

0.594 

.781 

0.391 

.513 

0.092 

.120 

19,30 

.128 

.478 

0.613 

.805 

0.404 

.531 

0.096 

.126 

20,27 

.177 

.546 

0.632 

.830 

0.414 

.543 

0.101 

.132 

21.23 

.236 

.616 

0.651 

.855 

0.425 

.558 

0.106 

.139 

22.19 

.283 

.685 

0.669 

.878 

0.434 

.570 

0.110 

.140 

23.16 

1.336 

.754 

0.685 

.894 

0.445 

.584 

0.115 

.151 

24.13 

1.388 

.823 

0.704 

.924 

0.454 

.596 

0.120 

.15Y 

25.09 

1.442 

.894 

0.722 

.948 

0.463 

.609 

0.125 

.164 

26.06 

1.496 

.965 

0.741 

.973 

0.472 

.619 

0.130 

.170 

27.02 

1.549 

2.034 

0.761 

.999 

0.479 

.629 

0.135 

.177 

27.99 

1  603 

2.105 

0.780 

1.023 

0.486 

.638 

28  95 

1  656 

2  175 

0^801 

1.052 

0.493 

.647 

30.88 

1.758 

2.309 

0.842 

1.106 

0.511 

.671 

32  81 

1  861 

2  444 

0  881 

1.157 

Q.K.O 

.696 

34.74 

l!966 

2^582 

0.919 

1  207 

o!547 

.718 

36.67 

2.070 

2.71£ 

0.955 

1.254 

0.565 

.742 

88.60 

0^992 

l!302 

0  579 

764 

40.63 

0.594 

.780 

The  ammonia  does  not  follow  the  absorption  laws  of 
Dalton,  inasmuch  as  the  quantity  of  ammonia  absorbed 
by  water  does  not  vary  directly  with  the  pressure. 


PROPERTIES  OP  AMMONIA.  103 

DIFFERENT  SYSTEMS  OF  REFRIGERATION. 

Both  the  anhydrous  liquor  and  the  ammonia  are 
used  in  refrigeration,  the  former  in  what  is  known  as  the 
Linde  or  compression  system,  and  the  latter  in  the  Carre 
or  absorption  system. 

TESTS  FOR  AMMONIA. 

As  the  boiling  point  of  pure  anhydrous  ammonia  is 
at  29°  below  zero -at  a  pressure  of  the  atmosphere  (30 
inches  of  mercury),  the  purity  of  anhydrous  ammonia 
may  be  tested  by  means  of  an  accurate  thermometer. 
The  same  is  inserted  into  a  flask  containing  the  ammonia 
in  a  boiling  condition,  and  provided  with  a  tube  to  carry 
off  the  obnoxious  vapor.  If  the  boiling  temperature 
differs  materially  from  the  above  (allowance  being  made 
for  the  barometric  pressure),  it  demonstrates  that  the 
ammonia  is  not  pure.  If  after  the  ammonia  is  evapo- 
rated, an  oily  or  watery  residue  is  left  in  the  flask,  the 
name  is  also  attributable  to  impurities.  Ammonia  leaks 
are  generally  easily  detected  by  the  smell  or  by  the  white 
fumes  which  form  when  a  glass  rod  moistened  with  hy- 
drochloric acid  is  passed  by  the  leak. 

If  traces  of  ammonia  are  to  be  detected  in  water  or 
in  brine  it  is  best  to  use  "Nessler's  Reagent,"  which  is 
prepared  as  follows : 

Dissolve  17  grams  of  mercuric  chloride  in  about  300 
cc.  of  distilled  water ;  dissolve  35  grams  of  potassium 
iodide  in  100  cc.  of  water ;  add  the  former  solution  to 
the  latter,  with  constant  stirring,  until  a  slight  perma- 
nent red  precipitate  is  produced.  Next  dissolve  120 
grams  of  potassium  hydrate  in  about  200  cc.  of  water ; 
allow  the  solution  to  cool ;  add  it  to  the  above  solution, 
and  make  up  with  water  to  one  liter,  then  add  mercuric 
chloride  solution  until  a  permanent  precipitate  again 
forms;  allow  to  stand  till  settled,  and  decant  off  the 
clear  solution  for  use ;  keep  it  in  glass  stoppered  blue 
bottles,  and  set  away  in  a  dark  place  to  keep  it  from 
decomposing. 

The  application  of  this  reagent  is  very  simple,  a  few 
drops  of  the  same  being  added  to  the  water  or  brine  in 
question,  contained  in  a  test  tube  or  a  small  glass  of  any 
other  kind.  If  the  smallest  trace  of  ammonia  is  present 
a  yellow  coloring  of  the  liquid  will  take  place,  which 
turns  to  a  full  brown  when  the  quantity  of  ammonia 
present  is  larger- 


104  MECHANICAL  REFRIGERA? MX. 

TESTING  AMMONIA. 

The  purity  of  anhydrous  ammonia  is  practically 
tested  by  allowing  the  same  to  evaporate  from  a  flask 
placed  in  water  and  provided  wifch  a  cork  and  bent  tube 
to  carry  off  the  obnoxious  water.  If  after  the  evapora- 
tion a  notable  oily  or  watery  residue  is  left  it  is  attribut- 
able to  impurities.  The  boiling  point  may  be  observed 
at  the  time  (it  is  29-30°  F.  below  zero),  and  if  any  perma- 
nent gases  are  given  off  when  the  tube  carrying  off  the 
ammonia  vapor  is  discharged  into  water  they  may  be 
tested  for  their  inflammability.  However,  these  latter 
two  tests  will  hardly  prove  satisfactory  except  in  the 
hands  of  an  experienced  chemist. 

In  order  to  test  the  liquid  residue  in  anhydrous  am- 
monia, Faurot  used  a  glass  tube  about  six  and  one-half 
inches  deep  and  one  and  one-eighth  inches  in  diameter, 
and  drawn  out  to  a  narrow  tube  at  the  bottom,  the  latter 
being  divided  in  fractions  of  a  centimeter,  while  the 
whole  tube  contains  about  100  cubic  centimeters.  The 
open  top  may  be  closed  with  a  rubber  cork  having  a  vent 
tube  of  glass,  the  outer  portion  of  which  is  bent  down  close 
to  the  large  tube,  so  that  the  whole  may  be  placed  in  a 
glass  of  water  after  the  tube  has  been  filled  to  about 
half  with  the  anhydrous  ammonia  to  be  tested.  The 
ammonia  will  now  boil  away  and  be  absorbed  by  the 
water  in  which  the  vent  tube  dips,  and  the  amount  or 
percentage  of  any  residue  that  may  be  left  can  be  readily 
estimated  by  the  readings  on  the  graduated  portion  of 
the  tube.  Permanent  gases  in  the  ammonia  will  manifest 
themselves  by  bubbles  passing  through  the  water. 

Ammonia  liquor  is  tested  for  its  strength  by  the 
hydrometer,  as  shown.  For  chemical  tests  it  should  be 
diluted  with  two  times  its  volume  of  distilled  water 
when,  after  acidification  with  hydrochloric  acid,  the 
addition  of  chloride  of  barium  solution  will  show  the 
presence  of  sulphates  by  a  white  precipitate.  In  the 
same  diluted  ammonia  liquor  clear  lime  water  will  show 
the  presence  of  carbonates  by  a  similar  precipitation. 
Chlorides  may  be  detected  by  acidifying  the  diluted  am- 
monia solution  with  nitric  acid  and  the  addition  of 
nitrate  of  silver  solution  by  the  formation  of  white  pre- 
cipitate. If  on  the  addition  of  nitric  acid  to  the  ammo- 
nia a  red  color  appears  it  indicates  traces  of  organic 
bases. 


WATER,  STEAM,  ETC.  105 

CHAPTER  III.—  WATER,  STEAM,  ETC. 

Water  is  a  combination  of  one  atom  of  oxygen  with 
two  atoms  (one  molecule)  of  hydrogen,  consequently  to  be 
designated  by  H  2O,  which  means  that  two  parts  by  weight 
of  hydrogen  are  combined  with  sixteen  parts  by  weight 
of  oxygen  to  form  eighteen  parts  (one  molecule)  of  water. 

FORMATION  OF  ICE. 

Water  solidifies  at  32°  F.,  but  in  very  fine  capillary 
tubes  the  freezing  point  may  be  depressed  for  20°  or 
more.  If  rigidly  confined  or  placed  under  pressure,  the 
freezing  point  is  depressed  likewise.  For  a  pressure  of  n 
atmospheres  the  freezing  point  is  depressed  for  n  X 
0.0135°  F.  •  Latent  heat  of  ice,  142  B.  T.  units. 

PROPERTIES  OF  ICE. 

The  ice  which  freezes  out  of  solutions  of  salt  or  other 
substance,  consists  of  pure  water,  the  impurities  remain- 
ing in  the  unfrozen  portion.  Ice  melts  at  32°  F.,  but  by 
a,  pressure  sufficiently  high  it  can  be  converted  into  liquid 
at  a  temperature  of  4°  F.  One  cubic  foot  of  ice  weighs 
998.74  ounces,  avoirdupois. 

STEAM. 

Water  volatilizes  like  any  other  liquid  in  accordance 
with  the  tension  of  its  vapor,  which  at  a  temperature  of 
212°  is  equal  to  the  tension  of  the  atmosphere  when  the 
water  boils,  and  is  converted  into  steam,  which  occupies 
about  1,700  times  the  volume  of  the  water.  The  water  dis- 
eociates  completely  at  a  temperature  of  about  4.500°,  but 
a  partial  decomposition  takes  place  at  a  lower  tem- 
perature. 

SATURATED  STEAM. 

When  steam  is  still  in  connection  with  water,  or  if 
it  is  in  such  condition  that  a  slight  decrease  of  tempera- 
tare  will  cause  liquefaction  of  some  of  the  steam,  it  is 
called  saturated  steam. 

The  pressure  of  saturated  steam  depends  on  its  tem- 
perature in  a  manner  approximately  expressed  by  Ran- 
kine's  formula: 


In  which  p  is  the  pressure  in  pounds  per  square  inch  at 
the  absolute  temperature  T  in  degrees  F.,  the  value  of 
constants  being:  A  =  6.1007,  log.  B  =  3.43642,  log.  (7=5.- 
69873. 


106  MECHANICAL  REFRIGERATION. 

TOTAL  HEAT. 

By  total  heat  of  steam  we  understand  that  quantity 
of  heat  required  to  raise  the  temperature  of  unit  weight 
of  water  from  the  freezing  point  to  any  given  tempera- 
ture, and  to  entirely  evaporate  it  at  that  temperature. 
The  total  heat,  I,  for  any  temperature,  <,  may  be  expressed 
by  the  formula: 

I  =1091,7  -f  0.305  (t— 32) 

LATENT  HEAT  OF  VAPORIZATION. 

If  the  heat  of  the  liquid,  g  (i.  e.,  the  amount  of  heat 
required  to  raise  the  temperature  of  unit  weight  of  water 
from  the  freezing  point  to  the  temperature  t)  is  sub- 
tracted from  the  total  heat,  I,  at  that  temperature,  we  find 
the  heat  of  volatilization,  7i,  viz. : 
h  =  l  —  g 

EXTERNAL  LATENT  HEAT. 

That  portion  of  the  latent  heat  required  to  overcome 
external  pressure,  or  the  external  latent  heat,  J7,  is 
expressed  by— 

„  *(»-».) 

~7~ 

In  which  formula  P  stands  for  external  pressure,  v  for 
the  volume  of  the  saturated  vapor,  v±  for  the  volume  of 
the  liquid,.and  /for  the  mechanical  equivalent  of  heat. 

INTERNAL  LATENT  HEAT. 

The  heat  required  to  bring  about  the  change  from 
the  liquid  to  the  gaseous  state,  t.  e.,  to  perform  the  work 
of  disintegration,  or  the  so-called  internal  latent  heat,  F, 
is  expressed  by  the  equation— 

F=h-E 

SPECIFIC  HEAT  OF  WATER. 

The  specific  heat,  c,  of  water  at  any  temperature,  t 
(expressed  in  degrees  Celsius),  is— 

c  =  1  +  0.00004  t  +  0.000000  tz 
See  also  table,  page  16. 

SPECIFIC  HEAT  OF  STEAM. 

The  specific  heat  of  superheated  steam  is  0.3643  at 
constant  volume  and  0.475  at  constant  pressure.  The 
specific  heat  of  saturated  steam,  s,  is  expressed  by  the 
equation— 


WATER,  STEAM,  ETC. 


107 


Which  is  negative  for  all  values  of  T  less  than  1436°  F., 
above  absolute  zero. 

SPECIFIC  HEAT  OF  ICE. 

The  specific  heat  of  ice  is  about  half  of  that  of  water, 
or  0.504. 

PROPERTIES  OF  SATURATED  STEAM,  AT  PRESSURE  FROM 
ONE  POUND  TO  200  POUNDS  ON  THE  SQUARE  INCH. 


PRESSURE 
ABSOLUTE. 

HEAT,  IN  DEGREES,  FAHR. 

&*t 

11 

a~ 

s"*$$ 

«s^*(5  3 

»•§ 

f| 

g! 

In  Inches  of 

~f^ 

o^la 

'sal 

O  "p/*-? 

•> 

Mercury 
at  32°. 

Temperature. 

Latent 

Heat. 

Total  Heat. 

SS31 
Ii»J 

IK 

«  §  bo 

•iii 

Dif. 

Dif. 

prlb 

prlb 

i 

2.0375 

102. 

1,043.05 

1,145.05 

20,890 

.0020 

.037 

5 

10.1875 

162.37 

9i26 

1,001.9 

1,163.46 

£82 

4,627 

.0135 

.167 

10 

20.375 

193.29 

4.93 

979.60 

1,172.89 

1.50 

2,429 

.0257 

.318 

15 

30  5625 

213.07 

3.47 

965.85 

1,178.92 

1.05 

1,669 

.0373 

.463 

eo 

40.75 

228. 

2.8 

955.5 

1,183.5 

.8 

1,880 

.0487 

.604 

25 

50.9375 

240.2 

2.3 

947. 

1,187.2 

.7 

1,042 

.0598 

.742 

30 

61.125 

250.4 

2. 

939.9 

1,190.8 

.6 

881 

.0707 

877 

35 

71.3125 

259.3 

1.7 

933.7 

1,193. 

764 

.0815 

1.012 

40 

81.5 

267.3 

1.5 

928.1 

1,195.4 

) 

676 

0921 

.142 

45 

91.6875 

274.4 

1.4 

923.2 

1,197.6 

608 

.1025 

.272 

50 

101.875 

281. 

1.3 

918.6 

1,199.6 

| 

652 

.1129 

.402 

55 

112.0625 

287.1 

1.2 

914.4 

1,201.5 

506 

.1232 

.529 

60 

122.25 

292.7 

1  1 

910.5 

1,203.2 

'.3 

467 

.1335 

.654 

65 

132.4376 

298. 

1.1 

906.8 

1,204.8 

.3 

434 

.1436 

1.779 

70 

142.625 

302.9 

1. 

903.4 

1,206.3 

.3 

406 

.1536 

1.904 

75 

152.8125 

307.5 

.9 

900.3 

1,207.8 

.3 

381 

.1636 

2.029 

80 

163. 

312. 

.9 

897.1 

1,209.1 

.2 

359 

.1736 

2.151 

85 

173.1875 

316.1 

.8 

894.3 

1,210.4 

.3 

340 

.1833 

2.271 

90 

183.375 

320.2 

.8 

891.4 

1,211.6 

.2 

323 

.1930 

2.391 

95 

193.5625 

324.1 

.8 

888.7 

1,212.8 

.3 

807 

.2030 

2.511 

100 

203.75 

327.8 

886.1 

1,213.9 

.2 

293 

.2127 

2.631 

105 

213.9375 

331.3 

i7 

1,215.0 

.2 

281 

.2224 

2.751 

110 

224.125 

334.6 

.6 

881  .'4 

1,216.0 

.2 

269 

.2319 

2.871 

115 

234.3125 

338. 

.6 

879. 

1,217.0 

.2 

259 

.2410 

2.990 

120 

244.5 

341.1 

.6 

876.9 

1,218.0 

.2 

249 

.2503 

3.105 

125 

254.6875 

344.2 

.6 

874.7 

1,218.9 

.2 

239 

.2598 

3.227 

130 

264.875 

347.2 

.6 

872.6 

1,219.8 

.2 

231 

.2693 

3.347 

135 

275.0625 

350. 

.5 

870.7 

1,220.7 

.1 

223 

.2788 

3.467 

140 

285.25 

352.9 

.6 

868.6 

1,221.5 

.1 

216 

.2883 

3.582 

145 

'295.4375 

.6 

866.8 

1,222.4 

.2 

209 

.2978 

8.697 

150 

305.625 

358^3 

.5 

864.9 

1,223.2 

.2 

203 

.3073 

3.809 

156 

315.8125 

360.9 

.5 

863.1 

1,224. 

.2 

196 

.3168 

3.927 

130 

326. 

363.4 

.5 

861.4 

1,224.8 

.2 

191 

.3263 

4.042 

765 

336.1875 

365.9 

.5 

859.7 

1,225.6 

.2 

186 

.3353 

4.157 

170 

346.375 

368.2 

.4 

858.1 

1,226.3 

.2 

181 

.3443 

4.270 

175 

356.5625 

370.6 

.5 

856.4 

1,227. 

.1 

176 

.3633 

4.383 

180 

366.75 

372.9 

.4 

854.8 

1,227.7 

.1 

172 

.3623 

4.495 

185 

376.9375 

375.  3 

.5 

853.1 

1,228.4 

.1 

168 

.3713 

4.607 

190 

387.125 

377.5 

.4 

851.8 

1,229.1 

.1 

164 

.3800 

4.720 

195 

396.3125 

379.7 

.4 

850.1 

1,229.8 

.2 

160 

.3888 

4.832 

?00 

407.5 

381.7 

.3 

848.6 

1,230.3 

.1 

157 

.3973 

4.945 

SPECIFIC   VOLUME  OF    STEAM. 

The  specific  volume  v,  of  steam,  in  accordance  with 
the  experiments  of  Tate  and  Fairbairn,  may  be  expressed 
by  the  formula-  25  62,_  49513 

r/>-j-0.72 


108  MECHANICAL  REFRIGERATION. 

VOLUME  AND  WEIGHT  OF   WATER. 

The  volume  of  water  does  not  change  in  direct  propor- 
tion with  the  temperature,  its  greatest  density  being  at 
39°  F.,  at  which  one  cubic  foot  weighs  62.425  pounds.  At 
32°  it  weighs  62.418,  at  62°  it  weighs  62.355,  and  at  the 
boiling  point  it  weighs  59.640  pounds.  One  cubic  foot  of 
water  is  generally  taken  at  62.5  pounds  =  7.  48  U.  S.  gal- 
lons ;  one  cubic  inch  of  water  =  .036  pounds  ;  one  cubic 
foot  of  water  =  6.2355  imp.  gallons,  or  7.48  U.  S.  gallons; 
one  U.  S.  gallon  of  water  =  8.34  pounds;  one  U.  S.  gallon 
of  water  =  231  cubic  inches. 

PRODUCTION  OF  STEAM. 

The  economical  production  of  steam  for  industrial 
purposes  is  chiefly  a  question  of  fuel  and  the  proper  con- 
struction of  boilers,  grates,  etc.,  and  has  been  alluded  to 
in  the  chapter  on  heat  under  the  headings  relating  to 
fuel.  For  satisfactory  arrangements  as  to  boilers,  etc., 
it  may  be  assumed  that  one  pound  of  fair  average  coal 
will  produce  about  eight  pounds  of  steam,  more  or  less. 

WORK  DONE  BY  STEAM. 

The  theoretical  ability  of  steam  to  do  a  certain 
amount  of  work  is  governed  by  the  laws  of  thermody- 
namics above  set  forth,  and  the  practical  yield  depends 
on  a  great  many  details  in  the  mode  of  applying  the 
force  of  steam  practically,  the  consideration  of  which  is 
beyond  the  limits  of  this  treatise.  For  rough  estimates, 
it  is  assumed  that  it  requires  from  fifteen  to  thirty  pounds 
of  steam  to  produce  a  horse  power,  according  to  per- 
fection of  engine,  per  hour. 

HEATING  AREA  OF  BOILER. 

If  H  is  the  nominal  horse  power  of  a  boiler  and  A 
the  effective  heating  area  of  the  same,  Box  finds  that  — 


A  nominal  horse  power  requires  from  0.6  to  1.2 
square  feet  of  grate  surface  between  the  limits  of  sixty 
and  three  horse  powers. 

PRIMING. 

The  water  which  is  mechanically  drawn  over  from 
the  boiler  with  the  steam  is  called  priming,  and  may  be 
determined  in  the  following  manner  given  by  Clark. 
Blow  a  quantity  of  the  steam,  the  amount  of  priming  in 
which  it  is  desired  to  ascertain,  into  a  vessel  holding  a 


WATER,  STEAM,  ETC.  109 

given  weight  of  cold  water,  noting  the  pressure  and  the 
weight  of  the  steam  blown  in,  and  the  initial  and  final 
temperatures  of  the  mixture.  An  addition  is  to  be  made 
to  the  initial  weight  of  water,  to  represent  the  weight  of 
water  equivalent  to  that  of  the  vessel  containing  the 
water,  in  terms  of  their  respective  specific  heats.  A  cor- 
responding addition  is  to  be  made  for  such  portion  of  the 
apparatus  as  is  immersed  in  the  water. 

Let  W=  weight  of  condensing  water,  plus  the  equiva- 
lent weight  of  the  receiver  and  apparatus  immersed  in 
the  water. 

w  =  weight  of  nominal  steam  discharged  into  the 
vessel  under  water. 

W  +  w  =  gross  weight  of  mixture  of  nominal  steam 
and  condensing  water. 

H  =  total  heat  of  one  pound  of  the  steam,  reckoned 
from  the  temperature  of  the  condensing  water. 

Hw  =  total  heat  delivered  by  the  gross  weight  of 
nominal  steam  discharged,  taken  as  dry  steam. 

t  =  initial  temperature  of  condensing  water. 

t'  =  final  temperature  of  condensing  water. 

s  =  augmentation  of  specific  heat  of  water  due  to  rise 
of  temperature. 

L==  latent  heat  of  one  pound  of  steam  of  the  given 
initial  pressure. 

Lw  =  latent  heat  of  steam  discharged  into  the  vessel, 
taking  it  as  dry  steam. 

P=  weight  of  priming  or  moisture  in  percentage  of 
the  gross  weight  of  nominal  steam. 

P_100.gw  —  [(W+w)X(tf  —  t  +  s)] 
Lw 

FLOW  OF  STEAM. 

The  flow  of  steam  through  pipes  takes  place  accord- 
Ing  to  Babcock  after  the  following  equation: 


In  which  formula  W  is  the  weight  of  steam  in  pounds 
which  will  flow  per  minute  through  a  pipe  of  the  length 
L  in  feet  and  the  diameter  d  in  inches,  when  pt  is  the 
initial  pressure,  p2  the  pressure  at  end  of  pipe,  and  D  the 
density  or  weight  per  cubic  foot  of  the  steam. 


110  MECHANICAL  REFRIGERATION. 

Steam  of  a  pressure  of  fifteen  pounds  per  square 
inch  (gauge  pressure)  flows  into  vacuum  with  a  speed  of 
1,550  feet  per  second,  and  into  air  with  a  speed  of  650  feet 
per  second.  , 

HYGROMETRY. 

Hygrometry  is  the  art  of  measuring  the  moisture  con- 
tained in  the  atmosphere,  or  of  ascertaining  the  hygro- 
metric  condition  of  the  latter. 

AIR  SATURATED  WITH  MOISTURE. 

The  amount  of  aqueous  vapor  which  can  be  held  by 
a  given  volume  of  air  increases  with  the  temperature 
and  decreases  with  the  pressure.  The  air  is  called  satu- 
rated with  moisture  when  it  contains  all  the  moisture 
which  it  can  contain  at  that  temperature.  The  degree  of 
saturation  or  hygrometric  state  of  the  atmosphere  is  ex- 
pressed by  the  ratio  of  the  aqueous  vapor  actually  present 
in  the  air  to  that  which  it  would  contain  if  it  were  satu- 
rated. In  accordance  with  Boyle's  law  the  degree  of 
saturation  may  also  be  expressed  by  the  ratio  of  the 
elastic  force  of  the  aqueous  vapor  which  the  air  actually 
contains  to  the  elastic  force  of  vapor  which  it  would  con- 
tain if  saturated. 

ABSOLUTE  MOISTURE. 

The  absolute  moisture  is  the  quantity  of  aqueous 
vapor  by  weight  contained  in  unit  volume  of  air. 

DEW  POINT. 

When  the  temperature  of  air  containing  moisture  is 
lowered  a  point  will  be  reached  at  which  the  air  is  satu- 
rated with  moisture  for  that  temperature,  and  a  further 
lowering  of  temperature  will  result  in  the  liquefaction 
of  some  of  the  moisture.  This  temperature  is  called  the 
dew  point. 

DETERMINATION  OF  MOISTURE. 

The  moisture  in  the  atmosphere  may  be  determined 
by  a  wet  bulb  thermometer,  which  is  an  ordinary  ther- 
mometer, the  bulb  of  which  is  covered  with  muslin  kept 
wet,  and  which  is  exposed  to  the  air  the  moisture  of 
which  is  to  be  ascertained.  Owing  to  the  evaporation  of 
the  water  on  the  muslin  the  thermometer  will  shortly 
acquire  a  stationary  temperature  which  is  always  lower 
than  that  of  the  surrounding  air  (except  when  the  latter 
is  actually  saturated  with  moisture).  If  t  is  the  temper- 


WATER,  STEAM,  ETC. 


Ill 


ature  of  Uie  atmosphere  and  it  the  temperature  of  the 
wet  bulb  thermometer  in  degrees  Celsius,  the  tension,  e, 
of  the  aqueous  vapor  in  the  atmosphere  is  found  by  the 
formula — 

e  =  et  —  0.00077  (t-tj  h^ 

e^  being  the  maximum  tension  of  aqueous  vapor  for  the 
temperature  tt  as  found  in  table,  and  h  the  barometric 
height  in  millimeters. 

If  ez  is  the  maximum  tension  of  aqueous  vapor  for 
the  temperature  t,  the  degree  of  saturation,  H,  is  ex- 
pressed by— 


H 


and  the  dew  point  is  also  readily  found  in  the  same  table, 
it  being  the  temperature  corresponding  to  the  tension  e. 

TABLE   SHOWING    THE  TENSION   OF    AQUEOUS  VAPOR  IN 
MILLIMETERS  OF  MERCURY,  FROM  — 30°  C.  TO  230°  C. 


Temp. 

Ten- 
sion. 

Temp. 

Ten- 
sion. 

Temp. 

Ten- 
sion. 

Temp. 

Ten- 
sion. 

^30 

.39 

21 

18.5 

94 

610.4 

105 

907 

-25 

.61 

22 

19.7 

94.5 

622.2 

107 

972 

—10 

.9 

23 

20.9 

95 

633.  H 

110 

1,077 

—15 

1.4 

24 

22.7 

95.5 

645.7 

115 

1,273 

—10 

2.1 

25 

28.6 

96 

657.5 

120 

1,491 

—  5 

3.1 

26 

25.0 

96.5 

669.7 

125 

1,744 

—  2. 

4.0 

27 

26.6 

97 

682.0 

130 

2,030 

—  1 

4.3 

28 

28.1 

97.5 

694.  G 

135 

2,354 

0 

4.6 

29 

29.8 

98 

707.3 

140 

2,717 

1 

4.95 

30 

81.6 

98.5 

721.2 

145 

3,125 

2 

5.3 

35 

41.9 

99 

732.2 

150 

3,581 

3 

5.7 

40 

55.0 

99.1 

735.9 

155 

4,088 

4 

6.1 

45 

71.5 

99.2 

738.5 

160 

4,551 

5 

6.5 

50 

92.0 

99.3 

741.2 

165 

5,274 

6 

7.0 

55 

117.5 

99.4 

743.8 

170 

5,961 

7 

7.5 

60 

148.Q 

09.5 

746.5 

175 

6,717 

8 

8.0 

65 

186.0 

99.6 

749.2 

180 

7,547 

9 

8.6 

70 

232.0 

99.7 

751.9 

185 

8,453 

10 

9.1 

75 

287.0 

99.8 

754.  fi 

190 

9,443 

11 

9.7 

80 

354.0 

99.9 

757.3 

195 

10,520 

12 

10.4 

85 

432.0 

100 

760 

200 

11,689 

13 

11.1 

90 

525.4 

100.1 

762.7 

205 

12,956 

14 

11.9 

90.5 

535.5 

100.2 

765.5 

210 

14,325 

15 

12.7 

91 

545.8 

100.4 

772.0 

216 

15,801 

16 

13.5 

91.5 

556.2 

100.6 

776.5 

220 

1?,39T 

17 

14.4 

92 

566.2 

101 

787.0 

225 

19,097 

18 

15.3 

92.5 

577.3 

102 

816 

230 

20,926 

19 

16.3 

93 

588.4 

103 

845 

20 

17.4 

93.5 

599.5 

104 

876 

Degrees  C 

Atmospheres. 


120  134  144  152  159  171  180  199  213  226 

2   3   4   5   6   8   10  15  20  25 

PSYCHROMETERS. 

Instead  of  the  wet  bulb  thermometer  alone  it  is 
more  convenient  to  use  two  exact  thermometers  com- 
bined (one  with  a  wet  bulb  and  the  other  with  a  dry 
bulb,  to  give  the  temperature  of  the  air)  to  determipe 


112 


MECHANICAL  REFRIGERATION. 


the  hygrometric  condition  of  the  atmosphere  or  of  the 
air  in  a  room.  Instruments  on  this  principle  can  be 
readily  bought,  and  are  called  psychrometers.  If  they 
are  arranged  with  a  handle,  so  that  they  can  be  whirled 
around,  they  are  called  "sling  psychrometers."  These 
permit  a  quicker  correct  reading  of  the  wet  bulb  ther- 
mometer than  the  plain  psychrometer,  in  which  the 
thermometers  are  stationary  and  are  impracticable  at  a 
temperature  below  32°  F.,  while  the  sling  instrument  can 
be  read  down  to  27°  F. 

The  following  table  can  be  used  to  ascertain  the  de- 
gree of  saturation  or  the  relative  humidity  : 

RELATIVE  HUMIDITY— PER  CENT. 


t  (Dry 
Ther.) 

Difference  between  the  dry  and  wet 
thermometers  (t—  t'). 

t  (Dry 
Ther.) 

0°.5 

1°.0 

1°.5 

2°.0 

2°.  5 

3°.0 

3°.  5 

4°.0 

4°.  6 

5°.r5°.5tJ°.0 

28 

94 

88 

82 

77 

71 

65 

60 

54 

49 

43 

38 

33 

28 

29 

94 

89 

83 

.77 

72 

66 

61 

56 

50 

45 

40 

35 

29 

30 

94 

89 

84 

78 

73 

67 

62 

57 

52 

47 

41 

36 

30 

31 

95 

89 

84 

79 

74 

68 

63 

58 

53 

48 

43 

38 

31 

32 

95 

90 

84 

79 

74 

69 

64 

59 

54 

50 

45 

40 

32 

33 

95 

CO 

85 

80 

75 

70 

66 

60 

56 

51 

47 

4i 

33 

34 

95 

91 

86 

81 

75 

72 

67 

62 

57 

53 

48 

44 

34 

35 

95 

91 

86 

82 

76 

73 

69 

65 

59 

54 

50 

45 

35 

36 

96 

91 

86 

82 

77 

73 

70 

66 

61 

56 

51 

47 

36 

3T 

96 

91 

87 

82 

78 

74 

70 

66 

62 

57 

53 

48 

37 

38 

96 

92 

87 

83 

79 

75 

71 

67 

63 

58 

51 

50 

38 

39 

96 

92 

88 

83 

79 

75 

72 

68 

63 

59 

5o 

52 

39 

40 

96 

92 

88 

84 

80 

76 

72 

68 

64 

60 

56 

53 

40 

The  hygrometer  of  Marvin  is  a  sling  psychrometer 
of  improved  and  approved  construction. 

HYGROMETERS. 

While  the  term  hygrometer  applies  to  all  instruments 
calculated  to  ascertain  the  amount  of  moisture  in  the 
air,  it  is  specifically  used  to  design  instruments  on  which 
the  degree  of  humidity  can  be  read  off  directly  on  a  scale 
without  calculation  and  table.  Their  operation  is  based 
on  the  change  of  the  length  of  a  hair  or  similar  hygro- 
scopic substance  under  different  conditions  of  humidity. 

DRYING  AIR. 

To  remove  moisture  from  air  more  or  less  saturated 
•with  it,  certain  so  called  hygroscopic  substances  which 
have  a  great  affinity  for  water  may  be  applied.  Chloride 
of  calcium,  dried  at  a  dul)  red  beat  and  powdered,  may  be 


WATER,  STEAM,  ETC.  113 

used  for  this  purpose,  and  when  spread  in  a  layer  %-inch 
thick  and  exposed  to  air  at  48°  F.,  with  a  humidity  of 
0.75,  will  absorb  per  square  foot  surface  in  each  one  of 
seven  succeeding  days  the  following  amounts  of  moist- 
ure: 1,368, 1,017,  958,  918,  900,  802  and  703  grains  respect- 
ively (Box). 

VAPORIZATION. 

The  vaporization  of  water  into  the  airxlepends  on 
the  hygrometric  state  of  the  atmosphere,  and  its  amount 
in  grains,  It,  per  square  foot  and  per  hour  with  air  per- 
fectly calm,  may  be  expressed  according  to  Box  by  the 
following  rule: 

B  =  (e2  —  e)\5 

When  the  air  into  which  the  water  evaporates  is  in 
motion  the  evaporation  proceeds  much  faster,  thus :  For 
a  fresh  breeze— 

R=(e2  —  e)QQ 
for  a  strong  wind — 

R=(e2—e)l32 
and  for  a  gale — 

E=(e2  —  e)188. 

The  refrigeration  which  is  produced  by  the  vaporiza- 
tion of  water  into  the  air  is  about  900  B.  T.  units  for  each 
pound  of  water  evaporated,  or  0.117  units  per  grain  of 
water  evaporated. 

PURITY  OF  WATER. 

As  natural  water  is  never  absolutely  pure  it  is  fre- 
quently of  importance  to  ascertain  the  degree  of  purity 
of  a  water  for  certain  purposes.  The  requirements  to 
be  made  in  regard  to  the  purity  of  a  water  vary  with  the 
purposes  for  which  it  is  to  be  used ;  water  may  be  very  good 
for  drinking  purposes,  but  at  the  same  time  it  may  be  too 
hard  for  boiler  feeding ;  and  on  the  other  hand  a  water 
may  be  good  for  boiler  feeding,  yet  it  may  be  too  impure 
(bacteriologically)  for  drinking  purposes.  Similar  dis- 
tinctions obtain  in  other  respects,  so  that  it  is  impracti- 
cable to  give  general  rules  for  the  valuation  of  a  water, 
unless  they  are  based  on  an  exact  chemical  analysis  of 
the  same.  The  crude  chemical  tests  which  are  fre- 
quently recommended  in  this  connection  are  of  little  or 
no  value  in  most  cases,  and  more  frequently  they  are 
misleading.  They  generally  only  give  qualitative  indi- 
cations, but  in  order  to  be  able  to  judge  a  water  correctly 
the  relative  quantities  of  its  constituents  must  be  known. 


114  MECHANICAL  REFRIGERATION. 

CHAPTER  IV.-THE    AMMONIA    COMPRESSION 
SYSTEM. 

GENERAL   FEATURES. 

The  refrigeration  in  this  system  is  brought  about  by 
the  evaporation  of  liquid  anhydrous  ammonia,  which 
takes  place  in  coils  of  pipe  termed  the  expander  or  refrig- 
erating coils.  These  coils  are  either  placed  in  the  rooms 
to  be  refrigerated,  or  they  are  immersed  in  a  bath  of  salt 
brine,  which  absorbs  the  cold.  The  salt  brine  is  circu- 
lated in  pipes  through  the  rooms  to  be  refrigerated  by 
means  of  a  pump.  The  ammonia,  after  having  expanded, 
is  compressed  again  by  means  of  a  compression  pump 
called  the  compressor  into  another  system  of  pipes  called 
the  condenser.  The  condenser  -is  cooled  off  by  running 
water,  which  takes  away  from  the  ammonia  in  the  coils 
the  heat  which  it  has  acquired  through  the  compression, 
as  well  as  the  heat  which  it  has  absorbed  while  having 
evaporated  in  the  expander.  Owing  to  both  pressure  and 
withdrawal  of  heat,  the  ammonia  assumes  its  liquid  form 
again  to  pass  again  into  the  expander,  thus  repeatirv# 
its  circulation  over  and  over  again. 

THE  SYSTEM  A  CYCLE. 

The  refrigerating  contrivance  above  described  em- 
bodies a  perfect  cycle  of  operations.  The  working  sub- 
stance, ammonia  in  this  case,  returns  periodically  to  its 
original  condition.  During  each  period  a  certain  amount 
of  heat,  partly  in  the  refrigerator  and  partly  during  com- 
pression (from  work  converted  into  heat),  is  added  to  the 
working  substance  and  an  exactly  equivalent  amount  is 
abstracted  from  the  working  substance  in  the  condenser 
by  the  cooling  water. 

THE  COMPRESSOR. 

The  compressor  is  a  strongly  constructed  cylinder  in 
which  a  piston  moves  to  and  fro,  having  a  valve  through 
which  the  expanded  ammonia  from  the  refrigerating  coils 
enters  and  another  through  which  it  is  forced  into  the  con- 
denser. A  double-acting  compressor  has  two  valves  at 
each  end  of  the  compressor  cylinder,  and  the  packing 
for  the  piston  rod  must  be  made  sufficiently  long  and  tight 
to  withstand  the  pressure  of  the  ammonia.  The  com- 
pressor, like  all  other  parts  of  the  ammonia  system, 
must  be  made  of  steel  and  iron,  no  copper  or  brass  being 
admissible, 


THE   AMMONIA  COMPRESSION    SYSTEM.  H5 

During  the  compression  stage  a  certain  amount  of 
heat  is  evolved.  If  not  otherwise  stated,  it  is  assumed  in 
the  following  discussion,  that  enough  heat  is  removed 
during  compression  to  keep  the  vapor  always  in  a  satu- 
rated condition. 

REFRIGERATING  EFFECT  OF  CIRCULATING  MEDIUM. 

To  arrive  at  numerical  values  of  the  quantities  in- 
vol ved  in  the  refrigerating  process  we  may  first  determine 
the  theoretical  refrigerating  effect,  r,  of  the  circulating 
medium. 

If  t  be  the  temperature  of  the  condenser,  that  is,  the 
temperature  of  the  cooling  water  leaving  the  condenser; 
if  tj  be  the  temperature  of  the  refrigerator,  that  is,  the 
temperature  of  the  brine  leaving  the  refrigerator;  if  s  is 
the  specific  heat  of  the  circulating  liquid,  and  if  /it  is  the 
latent  heat  of  vaporization  of  one  pound  of  the  circulating 
medium  in  thermal  units  at  the  temperature  tlt  we  find 
the  refrigerating  effect,  r,  of  one  pound  of  the  circulating 
fluid,  expressed  in  thermal  units  after  the  following 
formula: 

r=7i1  —  (t — £t)  s 

The  term  (t  —  tt)  s  represents  the  refrigeration  re- 
quired to  reduce  the  temperature  of  the  circulating  fluid 
from  the  temperature  t  to  the  temperature  t±. 

Practically  speaking,  the  temperature  of  the  ammonia 
in  condenser  will  always  be  a  few  degrees  higher  than  the 
water  leaving  the  condenser,  and  the  ammonia  in  refriger- 
ating coil  will  always  be  a  few  degrees  (5  to  10)  lower  than 
the  outgoing  brine. 

WORK  OF  COMPRESSOR. 

If  the  cycle  of  operation  was  a  perfect  reversible  one, 
the  work  required  from  the  compressor  for  every  pound 
of  the  liquid  circulating  would  be  to  lift  the  amount  of 
heat,  r,  from  the  temperature  t±  to  the  temperature  t. 
As  explained  already,  this  is  not  the  case,  and  the  whole 
amount  of  heat  as  represented  by  the  latent  heat  of  vap- 
orization, namely,  /it,  is  to  be  lifted  by  the  compressor 
through  the  range  of  temperature  indicated.  Hence  the 
work  theoretically  required  from  the  compressor  ex- 
pressed in  thermal  units,  TF,  is  therefore — 


X 

T  representing  the  temperature  of  the  refrigerator  ex- 
pressed in  degrees  of  absolute  temperature  ( tv  -f  460 ), 


116         MECHANICAL  REFRIGERATION. 

HEAT  TO  BE  REMOVED  IN  THE  CONDENSER. 

The  theoretical  number  of  heat  units,  D,  which 
would  have  to  be  removed  by  the  condenser  water  per 
pound  of  refrigerating  fluid  in  circulation  in  the  system, 
if  the  circulating  fluid  in  compressor  were  always  kept 
in  a  saturated  condition  from  without  by  removing  the 
surplus  heat,  could  be  expressed  as  follows: 

D  =  h, 

h  being  the  latent  heat  of  volatilization  of  one  pound  of 
the  circulating  liquid  at  the  temperature  of  condenser  (t). 

The  whole  amount  of  heat,  Dj,  to  be  removed  when 
including  that  which  would  cause  superheating  of  the 
fluid  in  compressor,  may  be  theoretically  expressed  as 
follows:  -„  t—t< 

-Pi=      T      fri+fei-g(*—  *i). 

AMOUNT  OF  SUPERHEATING. 

The  amount  of  heat,  £,  liable  to  cause  superheating 
may  therefore  be  expressed  by  the  formula— 
S=D1  —  D,  or     fc.fc 


COUNTERACTING  SUPERHEATING. 

The  surplus  heat  in  compressor  is  removed  in  various 
ways  :  by  injecting  refrigerated  oil,  by  surrounding  the 
compressor  with  a  cold  water  jacket,  or  by  carrying 
liquid  ammonia  into  the  compressor,  etc.  While  there 
is  no  doubt  as  to  the  advisability  of  preventing  super- 
heating as  much  as  possible,  the  theoretical  discussions 
regarding  the  relative  merit  of  these  expedients  do  not 
quite  agree  among  themselves,  nor  with  practical  expe- 
rience, and  it  would  appear  that  besides  theoretical  con- 
siderations certain  practical  points  have  some  bearing  on 
this  question,  especially  the  degree  to  which  the  preven- 
tion of  superheating  is  effected. 

AMOUNT  OF  AMMONIA  IN  COMPRESSOR. 

The  additional  amount  of  liquid  ammonia  that  would 
have  to  be  carried  into  the  compressor  with  every  pound 
of  ammonia  vapor  entering  the  same,  in  order  to  keep 
the  latter  saturated  during  compression,  may  be  ex- 
pressed by  the  formula  — 

P=F- 
/i, 

in  which  P  stands  for  pounds  of  liquid  ammonia  so  re- 
quired. 


THE  AMMONIA  COMPRESSION  SYSTEM.  117 

NET  THEORETICAL  REFRIGERATING  EFFECT. 

The  ammonia  required  to  keep  the  vapor  saturated 
in  compressor  has  to  be  cooled  down  from  the  tempera- 
ture t  to  the  temperature  t},  and  the  refrigeration  is  re- 
duced to  that  extent.  Accordingly  the  net  refrigerating 
effect,  rt,  of  every  pound  of  circulating  liquid  volatilized 
in  refrigerator,  in  case  of  wet  compression  is  expressed 
by  the  formula: 

or 

rt  =  ht  —  (t  —  t±)s  —  T  —  s(t  —  tt). 
ftj 

VOLUME  OF  THE  COMPRESSOR. 

The*  volume  of  the  compressor  is  expressed  by  the 
amount  of  space  through  which  the  piston  travels  each 
stroke.  If  r  be  the  radius  of  the  compressor  and  b  the 
length  of  stroke  in  feet,  the  active  volume  of  the  com- 
pressor, V,  is  — 

V=  r2  X  b  X  3.145  cubic  feet. 

If  r  and  b  are  expressed  in  inches  the  formula  would 
become— 

,,,       r2bX  3.145       ,.     . 

cubic  feet. 


CUBIC  CAPACITY  OF  COMPRESSOR. 

The  cubic  capacity  of  a  compressor  may  be  expressed 
by  the  amount  of  space  which  the  piston  travels  through 
in  one  minute,  only  one  way  being  counted  in  a  single- 
acting,  and  both  ways  being  counted  for  each  revolution 
in  a  double-acting  compressor.  If  m  is  the  number  of 
revolutions  per  minute,  r  the  radius  and  6  the  length  of 
stroke  in  feet  of  a  compressor,  the  capacity  of  the  same, 
C,  if  single-acting,  is  expressed  by  the  formula  : 

C  =  r2  x3.145x&Xm  cubic  feet  per  minute; 

if  double-acting,  it  is  twice  that.    If  r  and  b  are  given  in 
inches,  the  product  must  be  divided  by  1,728  to  find  (7. 

CLEARANCE. 

As  the  piston  does  not  exactly  touch  the  cylinder 
ends,  leaving  always  more  or  less  dead  space  called  clear- 
ance, the  whole  of  the  above  capacity  is  not  available  on 
this  account,  and  from  5  per  cent  to  7  per  cent  may  be 
deducted  from  it  for  clearance.  This  may  be  called  the 
reduced  capacity  of  the  compressor. 


118  MECHANICAL  REFRIGERATION. 

The  exact  percentage  of  clearance  depends  on  a 
number  of  conditions,  and  may  be  approximately  deter- 
mined after  the  following  equation: 


V 

In  this  equation  (7  is  the  theoretical  capacity  of 
a  compressor,  and  C±  the  corrected  or  reduced  capac- 
ity in  accordance  with  clearance.  V  is  the  volume 
traversed  by  piston  in  each  stroke  in  cubic  feet,  n  the 
actual  clearance  space  left  between  piston  and  cylinder 
in  cubic  feet,  w  and  wt  the  weights  of  equal  volumes  of 
ammonia  at  the  pressure  in  condenser  and  refrigerator 
respectively. 

REFRIGERATING  CAPACITY  OF  COMPRESSOR. 

The  refrigerating  capacity  of  a  compressor  does  not 
alone  depend  on  its  cubic  capacity,  but  also  on  surround- 
ing circumstances,  especially  the  temperature  in  con- 
denser and  refrigerator  coils,  and  can,  therefore,  not  be 
exactly  determined  without  these  data.  For  rough  esti- 
mates it  may  be  assumed,  however,  that  under  quite 
frequently  prevailing  conditions  a  cubic  compressor 
capacity  per  minute  of  four  feet  will  be  equivalent  to  a 
capacity  of  one  ton  refrig.  in  twenty-four  hours.  (Fifty- 
six  inches  double-acting  compressor  capacity  sixty  revo- 
lutions. )  If  GI  is  the  reduced  compressor  capacity  per 
minute  (that  is,  G  less  clearance)  the  corresponding  re- 
frigerating capacity,  jK,  expressed  in  tons  of  refrigera- 
tion in  twenty-four  hours,  may  be  found  after  the  follow- 
ing formula:  p  __  Ot  X  36  X  r 

:    vX  7,100 
or  approximately— 

-R  =  200  ^     ton8' 

In  this  formula  v  stands  for  the  volume  of  one  pound 
of  ammonia  vapor  in  cubic  feet  at  the  temperature  of 
the  refrigerator ;  the  sign  r  stands  for  the  maximum 
theoretical  refrigerating  capacity  for 'each  pound  of  am- 
monia passing  the  compressor. 

The  refrigerating  capacity  of  a  compressor,  expressed 
in  thermal  units,  Blt  per  hour,  is— 


THE  AMMONIA  COMPRESSION  SYSTEM.  H9 

AMMONIA  PASSING  THE  COMPRESSOR. 

The  amount  'of  ammonia,  K,  in  pounds  passing  the 
compressor  per  minute  is  expressible  thus: 

K—  G!  X  w  pounds, 

in  which  C^  stands  for  the  reduced  compressor  capacity 
per  minute  and  w  for  the  weight  of  one  cubic  foot  of 
ammonia  vapor  at  the  temperature  of  the  refrigerator  or 
expansion  coils. 

NET  REFRIGERATING  CAPACITY. 

As  the  last  four  formulae  allow  for  clearance,  but  not 
for  other  losses,  it  is  more  convenient  and  practically 
sufficiently  correct  in  most  cases  to  substitute  in  these 
formulae  Cfor  d,  and  reduce  the  refrigerating  capacity 
so  found  by  15  per  cent,  which  should  be  ample  for  all 
losses,  and  give  net  refrigerating  capacity. 

HORSE  POWER  OF  COMPRESSOR. 

If  W=  — rp^hi  (in  thermal  units)  is  the  power  re- 
quired by  the  compressor  to  lift  the  heat  which  became 
latent  by  the  evaporation  of  one  pound  of  ammonia  in 
refrigerator,  as  shown  before,  and  if  K  represents  the 
amount  of  ammonia  vapor  entering  the  compressor  per 
minute,  the  work  to  be  done  by  the  compressor  per  min- 
ute, Wit  expressed  in  thermal  units,  is— 
Wl=WxK  units. 

If  expressed  in  foot-pounds,  TF2,  it  is— 
W*  =778  WX  K  foot-pounds. 

And  if  expressed  in  horse  powers,  W3,  it  is— 

ITQQ 

W*  =  ~33W  WX  K="  0>°234  WK  h°rse  P°Wer* 
W3  =  0.0234^^/1,  x  C  X  w  horse  power. 

SIZE  OF  COMPRESSOR. 

In  order  to  determine  the  size  of  a  compressor  for  a 
given  refrigerating  duty  it  is  advisable  to  reduce  the 
latter  to  an  expression  of  heat -units  to  be  removed  per 
hour;  and  if  the  same  is  understood  to  represent  actual 
refrigerating  capacity,  some  15  per  cent  or  more,  ac- 
cording to  circumstances,  should  be  added  for  clearance 
and  other  losses,  and  in  case  the  refrigerating  capacity  is 
required  in  the  form  of  manufactured  ice  it  should  at 


120  MECHANICAL  REFRIGERATION, 

least  be  doubled.  The  reduced  refrigerating  duty  so 
obtained  we  will  callr2,  o  the  volume  *of  one  pound  of 
ammonia  gas  at  the  temperature  of  the  outgoing  brine, 
rt  the  refrigerating  effect  of  one  pound  of  ammonia  for 
the  temperatures  employed,  Fthe  active  volume  swept 
over  by  the  piston  in  each  revolution  (two  times  the 
volume  of  compressor  if  the  same  is  double-acting),  and 
m  the  number  of  revolutions  per  minute.  Signs  having 
this  meaning,  the  following  equations  obtain: 


In  this  case  Vm  signifies  the  compressor  capacity  per 
minute.    If  m  is  given— 


If  F  is  given— 

m  "  60Xr,F  revolutions- 

NUMBER  OF  REVOLUTIONS  AND  PISTON  AREA. 

The  number  of  revolutions  of  compressor  varies  with 
its  size  from  forty  to  eighty  revolutions  per  minute. 
When  the  compressor  is  worked  directly  by  a  steam  en- 
gine, as  is  generally  the  case,  the  number  of  revolutions 
of  the  compressor  is  governed  by  those  of  the  engine, 
and  the  area  of  the  compressor  piston  must  be  in  ac- 
cordance with  that  of  engine  piston.  The  product  of 
average  pressure  on  engine  piston  with  the  area  of  the 
latter  must  always  be  greater  than  the  product  of  the 
compressor  piston  area  multiplied  by  the  pressure  in  con- 
denser coil  if  both  the  engine  and  compressor  piston 
have  the  same  length  of  stroke.  If  the  stroke  of  com- 
pressor piston  is  shorter  than  that  of  engine  piston  its 
area  can  be  made  correspondingly  larger. 

USEFUL  AND  LOST  WORK  OF  COMPRESSOR. 

That  part  of  the  work  of  the  compressor  which  is  ex- 
pressed by  the  foregoing  equations -for  W^,  W2  or  W3 
may  be  considered  as  useful  work  of  the  compressor, 
while  what  work  is  done  by  the  compressor  in  excess  of 
that  amount,  due  to  superheating,  friction  and  other 
causes,  may  be  considered  as  lost  work.  The  smaller  the 
lost  work  the  more  perfect  is  the  operation  of  the  com- 
pressor. 


AMMONIA  COMPRESSION    SYSTEM.  121 

DETERMINATION  OF  LOST   WORK. 

The  lost  work  of  a  compressor  may  be  determined  in 
various  ways,  directly  by  interpretation  of  the  indicator 
diagram  and  also  indirectly  in  some  cases.  The  lost  work 
is  the  difference  between  the  actual  work  done  by  the 
compressor  and  that  theoretically  required  of  the  same, 
or  expressed  by  formula,  L  standing  for  lost  work  in 
thermal  units  and  W6  for  actual  compressor  work  in 
thermal  units: 

L=  WQ  —  Wi 

INDIRECT  DETERMINATION  OF  ACTUAL  WORK. 

In  a  machine  with  submerged  condenser,  the  actual 
work,  TF6,  of  the  compressor  may  be  approximately  de- 
termined in  T.  U.  per  hour  after  the  following  formula: 

W6  =  (T—T1)p  —  (t  —  tl)gs1 

in  which  formula  T  is  the  temperature  of  outgoing,  Tt  the 
temperature  of  incoming  condenser  water,  t  the  tempera- 
ture of  cold  brine,  tt  the  temperature  of  returning  brine, 
p  the  number  of  pounds  of  condensing  water  used  per 
hour,  g  the  number  of  pounds  of  brine  circulated  per 
hour,  and  s1  the  specific  heat  of  the  brine. 

The  actual  compressor  work  found  in  this  manner 
will  be  somewhat  larger  than  that  found  from  the  indi- 
cator diagram,  since  it  includes  the  lost  work  due  to  fric- 
tion in  the  compressor.  .  Allowance  must  also  be  made 
for  amount  of  superheating  neutralized  otherwise  than 
by  condenser  water. 

HORSE  POWER  OF  ENGINE. 

The  work  required  to  operate  the  compressor,  whether 
furnished  by  engine  direct  or  by  transmission  and  gear- 
ing, must  be  equal,  or  rather  somewhat  greater  than  the 
actual  work  of  the  compressor.  It  must  exceed  the  work 
shown  by  the  indicator  by  at  least  the  amount  due  to 
friction  of  piston,  etc.  It  is  safe  to  assume  that  the  in- 
dicated horse  power  of  an  engine,  JF7,  necessary  to  pro- 
pel a  compressor  of  a  theoretical  horse  power,  W3,  is  at 
least  about— 

W7  =  1.4  W3  horse  power. 

In  defective  machines  it  may  be  more;  seldom,  how- 
ever, it  will  be  less. 

WATER  EVAPORATED  IN  BOILER. 

The  amount  of  w.iter  evaporated  in  boiler  (for  non- 
condensing  engine)  may  be  approximately  estimated  on 


122  MECHANICAL  REFBIGERATION. 

the  basis  that  twenty-five  pounds  of  water  are  needed 
per  hour  per  horse  power  in  a  well  regulated  boiler. 
The  amount  of  water,  J.,  evaporated  f  or  twenty-four  hours 
is,  therefore— 

A  =  25  X  24  X  W7  pounds. 

COAL  BEQUIBED. 

If  one  pound  of  coal  evaporates  n  pounds  of  water  the 
amount  of  coal,  F,  required  in  twenty-four  hours  is  ap- 
proximately— 


In  a  condensing  engine  about  fifteen  pounds  of  water 
are  used  per  horse  power  per  hour,  and  the  foregoing 
formula  in  that  case  reads — 

,,     15  X  24  X  W7 

—       n  P°unds' 

n  differs  for  various  kinds  of  fuel,  but  may  be  assumed 
equal  to  8  for  fair  average  coal. 

EFFICIENCY  OF  COMPRESSOR. 

The  term  efficiency  covers  a  variety  of  meanings,  and 
the  meaning  ought  to  be  expressed  clearly  in  each  case. 
Generally  efficiency  is  expressed  by  the  number  of  units 
of  heat  removed  from  the  refrigerator  for  every  thermal 
unit  of  work  done  by  compressor,  which  is  also  expressed 
by  the  quotient— 

_,  Heat  removed  in  refrigerator 

Work  done  by  compressor  in  T.  U. 

This  may  be  called  the  actual  efficiency  for  a  given 
case.  As  it  varies  not  only  with  the  machine,  but  also, 
and  most  decidedly  so,  with  the  local  condition  under 
which  it  works  (temperature  of  refrigerator  and  con- 
denser) it  affords  no  criterion  as  to  the  lost  work  done  by 
the  compressor,  i.  e.,  it  is  not  an  expression  for  the  degree 
of  perfection  of  the  compressor. 

In  order  to  obtain  an  expression  for  this  quality  we 
must,  according  to  Linde,  compare  the  actual  efficiency 
of  a  plant  with  the  maximum  theoretical  efficiency  of 
Uje  plant  when  working  under  the  same  condition.  The 
maximum  theoretical  efficiency,  E2,  is  expressed  by  Linde 
through  the  formula — 

T 
E2  =  Ti_  T 


TflE  AMMONIA  COMPRESSION  SYSTEM  123 

As  we  have  seen  above,  this  should  more  properly  be 
substituted  by  the  maximum  theoretical  efficiency,  E^ 
as  explained  in  the  above,  at  least  if  machines  with  the 
same  circulating  medium  are  to  be  compared,  viz.: 


i-*i) 

If  R  stands  for  the  heat  actually  removed  in  refrig- 
eration and  Q  for  work  actually  performed  by  compressor, 
as  ascertained  by  actual  observation  or  test,  we  have  for 
the  actual  efficiency,  E%  the  expression— 


The  ratio  or  proportion,  w,  between  the  actual  and  the 
theoretical  capacity  is  therefore— 

E 

n  =  -E[ 
or  if  we  insert  the  expressions  found  abore— 

«,_.    -RM<-*i) 

QT^-s(t-tJ} 

DIFFERENT  KINDS  OF  COMPRESSORS. 

There  are  many  constructive  details  in  valves,  etc.,  in 
the  different  makes  of  compressors  which  it  is  impracti- 
cable here  to  discuss.  The  principal  difference,  how- 
ever, is  due  to  the  different  methods  in  which  super- 
heating of  the  gas  during  compression  is  prevented  or  to 
whether  the  compressor  is  horizontal  or  vertical,  double 
or  single-acting,  etc.  By  way  of  example  we  mention 
only  a  few  typical  ones. 

THE  LINDE  COMPRESSOR. 

This  compressor  is  principally  used  for  wet  compres- 
sion, the  peculiarities  of  which  have  been  mentioned 
above ;  it  is  a  horizontal  double-acting  compressor  with 
a  deep  packing,  having  a  length  of  twelve  inches  or 
more  in  order  to  withstand  the  pressure  of  some  150  to 
180  pounds.  Since  ammonia  attacks  India  rubber,  the 
best  rubber  packings  for  compressors  are  inlaid  with 
cotton.  Selden's,  Oarlock's  and  Common  Sense  packing 
are  also  used. 


124 


MECHANICAL  REFRIGERATION. 


The  Boyle  compressor  is  vertical  and  single-acting, 
compressing  only  on  the  up  stroke.  The  gas  has  free  en- 
trance to  and  exit  from  the  cylinder  below  piston,  calcu 
lated  to  keep  cylinder  and  piston  cool.  The  extreme 
lower  portion  of  the  pump  forms  an  oil  chamber  to  seal 
the  stuffing  box  around  piston. 

THE  DE  LA  VERGNE  COMPRESSOR. 

This  compressor  is  also  a  vertical  compressor,  and 
superheating  is  counteracted  by  means  of  refrigerated 
oil,  which  is  circulated  through  the  compressor  by  means 
of  a  small  pump.  Another  object  of  the  oil  is  that  its 
presence  ahead  and  behind  the  piston  abolishes  the  evil 
effects  of  clearance,  or  at  least  lessens  the  same  mate- 
rially. It  furthermore  affords  excellent  lubrication  of 
the  moving  parts  and  helps  to  make  the  piston  tight. 

THE  WATER  JACKET  COMPRESSOR. 

This  form  of  compressor  is  mostly  vertical,  its  pecul- 
iarity being  that  the  superheating  is  prevented  by  circu- 
lating cold  water  or  brine  through  a  water  jacket  which 
surrounds  the  compressor. 

These  compressors  are  frequently  single-acting;  in 
this  case  a  shorter  stuffing  box  (causing  less  friction)  for 
piston  rod  may  be  used,  since  the  pressure  on  the  stuffing 
box  is  seldom  more  than  thirty  pounds. 

TABLE  SHOWING  REFRIGERATING  EFFECT  OF  ONE  CUBIC 

FOOT  OF  AMMONIA  GAS  AT  DIFFERENT  CONDENSER 

AND  SUCTION  (BACK)  PRESSURE  IN  B.  T.  UNITS. 


i 

«fd 

Temperature  of  the  Liquid  in  Degrees  P. 

0  to 

II! 

65°      70°       75°      80°       85°       90°       95°      100°      105° 

43  ® 

£  Q 

u  * 

Correspg.  Condenser  Pressure  (gauge)  Ibs.  per  sq.  in. 

§ 

OQ 

103     115       127      139       153       168       184       200       218 

g 

G.  Pres 

—27° 

1 

27.30 

27.01 

26.73 

26.44 

26.16 

25.87 

25.59 

25.30 

25.02 

—20° 

4 

33.74 

33.40 

33.04 

32.70 

32.34 

31.99 

31.64 

31.30 

30.94 

-15° 

6 

3ti.36 

36.48 

36.10 

35.72 

35.34 

34.96 

34.58 

34.20 

33.82 

—10° 

9 

42.28 

41.84 

41.41 

40.97 

40.54 

40.10 

39.67 

39.23 

38.80 

—  5° 

13 

48.31 

47.81 

47.32 

46.82 

46.33 

45.83 

45.34 

44.84 

44.35 

0° 

16 

54.88 

54.32 

63.76 

63.20 

52.64 

52.08 

61.52 

50.96 

50.40 

5° 

20 

61.50 

60.87 

60.25 

59.62 

59.00 

58.37 

67.75 

57.12 

56.50 

10° 

24 

68.66 

67.97 

67.27 

66.58 

65.88 

65.19 

64.49 

63.80 

63.10 

15° 

28 

75.88 

75.12 

74.  3  1 

73.59 

72.82 

72.06 

71.29 

70.53 

69.76 

20° 

33 

85.15 

84.30 

83.44 

82.59 

81.73 

80.88 

80.02 

79.17 

78.31 

25° 

39 

95.50 

94.54 

93.59 

92.63 

91.68 

90.72 

89.97 

88.81 

87.86 

80° 

45 

106.21 

105.15 

104.09 

103.03 

101.97 

100.91 

99.85 

98.79 

97.73 

51 

115.W, 

114.54123.39 

112.24 

111.09 

109.94 

108.79107.64 

106.49 

THfi  AMMONIA  COMPRESSION  SYSTEM. 


125 


TABLE  GIVING  NUMBER  OF  CUBIC  FEET  OF  GAS  THAT  MUST 

BE  PUMPED  PER  MINUTE  AT  DIFFERENT  CONDENSER 

AND  SUCTION  PRESSURES,  TO  PRODUCE  ONE 

TON  OF  REFRIGERATION  IN  24  HOURS. 


a 

0 

be£  a 

Temperature  of  the  Gas  in  Degrees  F. 

^ 

o>  & 

Ili 

65°      70°       75°      80°       85°       90°       95°      100°      105° 

S2 

g_£^ 

tJ  tiC 

rf  o 

!« 

o"o-Q 

Correspg.  Condenser  Pressure  (gauge)  Ibs.  per  sq.  in. 

OSH^ 
01 

103      115       127.     139       153       168       184       200       218 

—27° 

G.  Pres 
1 

7.22 

7.3 

7.37 

7.46 

7.54 

7.62 

7.70 

7.79 

7.88 

—20° 

4 

5.84 

5.9 

5.96 

6.03 

6.09 

6.16 

6.23 

6.30 

6.43 

—15° 

6 

5.35 

5.4 

,^.46 

5.52 

5.58 

5.64 

5.70 

5.77 

5.83 

—10° 

9 

4.66 

4.73 

4.76 

4.81 

4.86 

4.91 

4.97 

5.05 

5.08 

—  5° 

13 

4.09 

4.12 

4.17 

4.21 

4.25 

4.30 

4.35 

4.40 

4.44 

0° 

16 

3.59 

3.63 

3.66 

3.70 

3.74 

3.78 

3.83 

3.87 

3.91 

20 

3.20 

3.24 

3.27 

3.30 

3.34- 

3.38 

3.41 

3.45 

3.49 

10° 

24 

2.87 

2.9 

2.93 

2.96 

2.99 

3.02 

3.06 

3.09 

3.12 

15° 

28 

2.59 

2.61 

2.65 

2.68 

2  71 

3.73 

2.76 

2.80 

2.83 

20° 

33 

2.31 

2.34 

2.36 

2.38 

2.  41 

2.44 

2.46 

2.49 

2.51 

25° 

39 

2.06 

2.08 

2.10 

2.12 

2.15 

2.17 

2.20 

2.22 

2.24 

30° 

45 

1.85 

1.87 

1.89 

1.91 

1.93 

1.95 

1.97 

2.00 

2.01 

36° 

51 

1.70 

1.72 

1.74 

1.76 

1.77 

1.79 

1.81 

1.83 

1.85 

THE  ST.  CLAIR  COMPOUND  COMPRESSOR. 

This  is  a  combination  of  two  or  more  single-acting 
compressors  after  the  principles  of  compound  engines,  in 
such  a  way  that  the  ammonia  is  compressed  part  way  at 
a  lower  pressure  in  one  compressor  and  then  transferred 
to  another  compressor,  in  which  the  higher  compression 
is  applied  after  the  ammonia  has  passed  an  intermediate 
condenser. 

WATER  FOR  COUNTERACTING  SUPERHEATING. 

The  amount  of  refrigeration,  U,  required  to  counter- 
act the  superheating  of  ammonia  in  the  case  of  dry  com- 
pression may  be  expressed  by — 

U=SxKX  1440  units  in  twenty -four  hours. 

In  accordance  with  the  above  described  devices,  it  is 
removed  either  by  cooling  the  oil  or  by  introducing  water 
into  the  water  jacket.  The  amount  of  water  in  gallons, 
</,  used  in  the  latter  case  per  day  may  be  approximated 
by  the  formula— 


8.33 

t  being  the   temperature  of    the   water    leaving    the 
water  jacket,  and  tt  being  the  temperature  of  the  water 


126  MECHANICAL  REFRIGERATION. 

entering  the  water  jacket.    The  values  for  8  and  K  have 
been  given  on  pages  116  and  119. 

THE  BY  PASS. 

Most  refrigerating  machines  are  provided  with  a  con- 
trivance enabling  the  engineer  to  reverse  the  action  of 
the  compressor  in  such  a  way  as  to  exhaust  the  condenser 
and  compress  into  the  refrigerator  by  the  opening  and 
the  closing  of  appropriate  valves,  the  combination  of 
which  constitutes  what  is  called  the  by  pass. 

THE  OIL  TRAP. 

This  is  a  vessel  placed  between  the  compressor  and 
condenser,  through  which  the  compressed  vapor  of  am- 
monia is  made  to  pass  in  order  to  deposit  therein  the  oil 
drawn  over  with  the  ammonia  from  the  lubricating 
materials  used  for  oiling  the  stuffing  boxes,  etc.  The  in- 
let pipe  should  enter  the  trap  sideways,  so  that  the  vapor 
may  strike  vertical  surfaces  and  not  the  oil  lying  on  the 
bottom  of  the  trap.  In  some  instances  the  oil  trap  is 
also  surrounded  by  a  water  jacket. 

CONDENSER. 

The  condenser  consists  of  systems  of  pipes  or  coils 
into  which  the  compressed  ammonia  is  forced  by  the 
compressor.  These  coils  are  either  immersed  in  the 
cooling  water  (submerged  condenser)  or  the  cooling 
water  runs  or  trickles  over  them  (open  air,  surface  or  at- 
mospherical condenser).  In  passing  through  the  con- 
denser the  ammonia  yields  to  the  cooling  water  the  heal 
which  it  has  acquired  in  doing  refrigerating  duty  by  its 
evaporation,  and  the  heat  which  it  has  acquired  during 
compression,  the  mechanical  work  done  by  compression 
having  been  converted  into  its  equivalent  of  heat.  This 
amount  of  heat  is  also  equal  to  the  latent  heat  of  vola- 
tilization of  the  ammonia  at  the  temperature  of  the  con- 
denser, and  in  addition  to  that  the  superheating  which 
may  have  taken  place. 

SUBMERGED  CONDENSER. 

A  submerged  condenser  consists  of  one  or  more  sec- 
tions of  coils  of  1M  to  2-inch  pipe.  It  is  preferable  to 
have  a  number  of  sections,  connected  by  manifold  inlets 
and  outlets  in  such  a  way  that  one  or  more  sections  may 
be  shut  off  for  repairs  or  for  other  reasons.  Instead  of 
having  the  same  size  pipe  all  the  way  through,  the  pip$ 


THE  AMMONIA  COMPRESSION  SYSTEM.  127 

may  be  taken  of  larger  size  at  the  inlet  for  the  vapor, 
and  taper  down,  say,  from  2-inch  to  1-inch  toward  the 
outlet,  where  the  ammonia  is  more  or  less  liquid  already; 
occupying  a  smaller  space. 

The  hot  ammonia  vapors  enter  the  condenser  at  the 
top,  and  the  liquid  ammonia  leaves  at  the  bottom  where 
the  cold  water  enters  the  condenser,  which  in  turn  leaves 
the  condenser  at  the  top.  Special  attention  should  be 
paid  to  an  equal  distribution  of  the  water  over  the  bot- 
tom of  condenser,  and  a  stirring  apparatus  should  be 
provided  to  keep  the  water  in  motion  around  the  con- 
denser coils.  The  condenser  should  be  more  high  and 
narrow,  rather  than  short  and  wide,  in  order  to  assist  the 
natural  tendency  for  circulation. 

AMOUNT  OF  CONDENSER  SURFACE. 

The  efficiency  of  the  condenser  determines,  in  a  great 
measure,  the  economical  working  of  the  machine,  for 
which  reason  it  is  good  policy  to  have  as  much  condenser 
surface  as  practical  considerations  may  permit.  As  to 
the  actual  amount  of  condenser  surface  to  be  employed, 
practice  is  the  principal  guide,  and  it  has  been  found 
that  for  average  conditions  (incoming  condenser  water 
70°  and  outgoing  condenser  water  80°,  more  or  less)  for 
each  ton  of  refrigerating  capacity  (or  for  one-half  ton 
ice  making  capacity)  it  will  take  forty  square  feet  of  con- 
denser surface,  which  corresponds  to  sixty-four  running 
feet  of  2-inch  pipe,and  to  ninety  running  feet  of  1^-inch 
pipe.  Frequently  20  square  feet  of  condenser  surface,  and 
even  less,  are  allowed  per  ton  of  refrigeration  (double  that 
for  actual  ice  making  capacity),  but  this  necessitates 
higher  condenser  'pressure,  etc.,  and  is  deemed  poor 
economy  by  many  engineers. 

The  number  of  square  feet  of  cooling  surface,  Ft 
required  in  a  submerged  condenser  may  be  approximately 
calculated  after  the  formula  — 


in  which  fi  is  the  heat  of  vaporization  of  one  pound  of 
ammonia  at  the  temperature  of  the  condenser,  k  the 
amount  of  ammonia  passing  the  compressor  per  minute, 
and  ra  the  number  of  units  of  heat  transferred  per 
minute  per  square  foot  of  surface  of  iron  pipe  hav- 
ing saturated  ammonia  vapor  inside  and  water  outside. 
I  represents  the  temperature  of  the  ammonia  in  tbe 


128  MECHANICAL  REFRIGERATION. 

coils,  and  t^  that  of  the  cooling  water  outside  of  the  coils, 
i.  e.,  mean  temperature  of  the  inflowing  and  outflowing 
cooling  water. 

Taking  the  above  practical  figures  for  condenser 
surface  between  70°  and  80°  temperatures  as  a  guide, 
the  factor  m  is  equal  to  0.5,  so  that  the  formula  reads  : 


square  feet. 


This  formula,  like  others  which  have  been  given  on 
this  subject,  is  an  empirical  one,  but  it  has  the  advant- 
age of  simplicity,  and  yields  results  corresponding  to  the 
practical  data  given  above. 

The  number  of  square  feet  of  pipe  surface  can  readily 
be  converted  into  pipe  lengths  of  any  given  size  by  refer- 
ring to  the  table  on  dimensions  of  pipe. 

AMOUNT  OF  COOLING  WATER. 

The  heat  which  is  transferred  to  the  ammonia  while 
producing  the  refrigeration,  and  also  the  heat  equivalent 
to  the  work  done  upon  the  ammonia  by  the  compressor 
(superheating  being  prevented),  must  be  carried  away 
by  the  cooling  water,  expressed  in  thermal  units  ;  and 
speaking  theoretically,  the  sum  of  these  two  heat  effects 
is  equal  to  the  heat  of  vaporization  of  the  ammonia  at 
the  temperature  of  the  condenser.  On  the  basis  of  this 
consideration  the  amount  of  cooling  water  A,  in  pounds 
required  per  hour  may  be  expressed  by  the  formula— 

Ai  =  ft-^xeo  pounds 

t  —  LI 

or  in  gallons  after  division  by  8.33,  the  signs  having 
the  same  significance  as  in  the  foregoing  formula,  with 
the  exception  of  «,  which  represents  the  actual  tempera- 
ture of  the  outgoing,  and  <15  which  represents  the  actual 
temperature  of  the  incoming  cooling  water. 

Practically  the  amount  of  water  used  varies  all  the 
way  from  three  to  seven  gallons  per  minute  per  ton,  ice 
making  capacity  in  twenty-four  hours. 

ECONOMIZING  COOLING  WATER. 

Where  cooling  water  is  very  scarce,  and  especially 
where  atmospherical  conditions,  dryness  of  air,  etc.,  are 
favorable,  the  cooling  water  may  be  re-used  by  subject- 
ing the  spent  water  to  an  artificial  cooling  process  by 
running  the  same  over  large  surfaces  exposed  to  the  air 
jn  a  fine  spray. 


THE  AMMONIA  COMPRESSION  SYSTEM.  129 

A  device  of  this  kind  is  described  as  being  a  chimney- 
like  structure,  built  of  boards,  having  a  height  of  about 
twenty-six  feet,  the  other  dimensions  being  five  by  seven 
feet.  Inside  this  structure  are  placed  a  number  of  parti- 
tions of  thin  boards,  spaced  four  inches  apart,  extending 
to  within  six  feet  of  the  bottom  of  the  structure;  but 
the  lower  halves  of  these  partitions  are  placed  at  right 
angles  to  those  in  the  upper  portion,  this  arrangement 
giving  better  results  than  unbroken  partitions. 

The  water  to  be  cooled  enters  the  structure  at  the 
top,  where  by  the  use  of  funnel-shaped  troughs  it  is 
spread  evenly  over  the  partitions  and  walls,  and  flows 
downward  in  thin  sheets.  At  the  base  of  the  structure 
air  is  introduced  in  such  quantity  that  the  upward  cur- 
rent has  a  velocity  of  about  twenty  feet  per  second.  The 
air  meeting  the  downward  flow  of  water  absorbs  the 
heat  by  contact  and  also  by  vaporizing  about  2  per  cent 
of  the  water,  reducing  its  temperature  during  the  pass- 
age 27°,  or  from  83°  to  56°.  By  this  process  the  tempera- 
ture of  the  water  can  be  reduced  from  5°  to  15°  below  the 
temperature  of  the  air,according  to  the  amount  of  moist- 
ure in  the  latter.  The  chief  expense  to  be  considered  in 
the  process  of  re-cooling  condenser  water  is  the  lifting  of 
the  water  to  the  top  of  the  structure.  As  a  matter  of 
course  it  is  also  good  economy  to  use  the  hot  condenser 
water  for  boiler  feeding,  as  the  equivalent  of  heat  ab- 
sorbed by  the  same  is  saved  in  the  steam  boiler. 

OPEN  AIR  CONDENSER. 

In  the  open  .air  or  atmospherical  condenser  the  pipes 
through  which  the  ammonia  passes  are  arranged  in  the 
open  air,  exposed  to  a  constant  draft  of  air,  if  possible. 
The  cooling  water  trickles  over  the  pipes.  The  ammonia 
vapor  flows  in  opposite  direction,  entering  at  the  bottom 
of  the  condenser,  the  liquid  passing  off  to  the  side  into 
a  vertical  manifold  as  fast  as  it  is  condensed. 

Other  atmospherical  condensers  said  to  give  excellent 
results  are  made  in  vertical  sections  of  pipe,  each  section 
receiving  the  compressed  vapor  at  the  top  from  a  com- 
mon manifold,  and  discharging  the  liquid  at  the  bottom 
into  a  common  manifold,  which  leads  to  the  liquid  re- 
ceiver. PIPE  REQUIRED. 

The  amount  of  condensing  surface  for  an  open  air 
condenser  is  taken  at  the  rate  of  forty  square  feet  per 
too  of  refrigerating  capacity  (or  for  one-half  ton  of  ice 


130  MECHANICAL  REFRIGERATION. 

making  capacity).    This  is  equivalent  to  64  running  feet 
of  2-inch  pipe  or  90  running  feet  of  1^-inch  pipe. 

As  in  the  case  of  the  submerged  condenser,  much  less 
pipe  (twenty-five  square  feet  per  ton  of  refrigeration  and 
less)  is  frequently  used. 

WATER  REQUIRED. 

The  cooling  water  required  for  an  atmospheric  con- 
denser is  much  less  (upwards  of  50  per  cent  and  more) 
than  for  a  submerged  condenser,  since  the  action  of  water 
is  assisted  by  that  of  the  air  directly,  and  still  more  indi- 
rectly by  causing  some  of  the  cooling  water  to  evaporate, 
thus  bringing  about  an  extra  absorption  of  latent  heat. 

It  is  claimed  that  where  local  conditions  are  favorable, 
the  same  cooling  water  may  be  used  over  and  over  again 
in  an  atmospherical  condenser,  if  the  same  is  built  suffi- 
ciently high. 

Another  advantage  of  the  open  air  condenser  is  due 
to  the  fact  that  all  the  water  comes  in  direct  contact 
with  the  surfaces  to  be  cooled. 

CONDENSER  PRESSURE. 

The  pressure  in  the  condenser  depends  on  the  temper- 
ature of  the  condensing  water,  and  is  always  as  high  as  or 
higher  than  the  tension  of  ammonia  vapor  corresponding 
to  the  temperature  of  the  water  leaving  the  condenser 
(say  about  ten  pounds  higher). 

LIQUID  RECEIVER. 

Generally  a  vessel,  preferably  a  vertical  cylinder  hold- 
ing about  half  a  gallon  for  each  ton  of  refrigerating 
capacity  (in  twenty-four  hours)  of  the  machine,  is  placed 
between  the  condenser  and  the  expansion  valve  to  re- 
ceive and  store  the  liquefied  ammonia.  It  also  serves  as 
an  additional  oil  trap,  the  oil  being  heavier  than  the  am- 
monia settling  on  the  bottom,  where  its  presence  is  indi- 
cated by  a  gauge,  and  whence  it  can  be  withdrawn  by 
opening  a  valve.  A  second  gauge  may  be  provided  for  on 
the  liquid  receiver,  at  about  that  point  at  which  the 
pipe  carrying  the  ammonia  from  the  receiver  to  expander 
terminates  within  the  receiver,  in  order  to  show  that 
there  is  a  sufficiency  of  liquid  ammonia  in  the  latter. 

If  the  liquid  receiver  is  to  act  as  a  storage  room  for 
all  liquefiable  ammonia  in  the  plant  in  case  of  repairs, 
etc.,  it  must  be  considerably  greater  than  one-half  gal- 
lon per  ton  of  refrigerating  capacity.  In  this  case  it  is 


THE  AMMONIA  COMPRESSION  SYSTEM. 


131 


provided  with  waives,  and  they  should  never  be  closed 
unless  the  receiver  is  not  over  two-thirds  filled  with  am- 
monia. To  avoid  explosions  on  this  account  the  liquid 
receiver  should  be  made  big  enough  to  contain  the  whole 
charge  of  ammonia  twice  over. 

DIMENSIONS  OF  CONDENSERS. 

The  following  tables,  compiled  by  Skinkle,  give  the 
dimensions  of  both  submerged  and  atmospheric  con- 
densers of  some  plants  in  actual  operation,  and  allow 
much  more  pipe  for  the  atmospheric  than  for  the  sub- 
merged condenser : 

ATMOSPHERIC   CONDENSERS. 


W)  . 

SSc/5 

ill 

%8S 

12*4 
20 
30 
40 
50 
60 
80 

Refrigerating, 
Capacity. 
In  Tons. 

Condenser  Pans. 

Number  of 
Pipes  High. 

Number  of 
Pipes  Wide. 

0«;S 

a)  P*a 
Nr-  y 
%*<£ 

Length  of  Coil 
over  bends. 
Feet. 

Total  feet  of  i 
Pipe  in 
Condenser. 

Feet  of  Pipe  per 
Ton,  Ice  Mak- 
ing Capacity.  
Feet  of  Pipe  per 
Ton,  Refrigerat- 
ing Capacity.  ' 

o 

tU« 
K£ 

3 

o 

«! 

0        03 

aev 

m 

1  Thickness  of 
Iron. 
Inches. 

50 
75 
100 
125 
150 

21 

24«/2 

24y2 
241/2 

24H 
24V2 
Z1K 

10% 
10X 
14 
14 

!1 

17 

8 

1 

8 
8 
12 
12 

Aver 
Aver 

3-16 
3-16 
3-16 
3-16 
3-16 
3-16 
3-16 

age  f 
agef 

:  '40 
40 
50 
50 
90 
80 
80 

or  1 

orl>i 

5 
5 

7 
7 
7 
7 
7 

in. 
in. 

1 
1 
1 
1* 

1¥ 
'1« 
Pipe 
Ptpe 

17 
21 
21 
21 

21 
21 
24 

per 
per 

3,680 
4,440 
7,750 
7,750 
13,950 
12,400 
14,080 

ton, 
ton, 

294.4 
222. 
258.  a 
193.75 
279. 
206.6 
176. 

147.2 
126.8 
155. 
103.3? 
139.5 
99.2 
93.86 

263.42142.12 
192.12)  S8.79 

SUBMERGED    CONDENSERS. 


bp 

Tar 

iks. 

Ld 

«    '.  .- 

«»  i>» 

Ilce  Making 
Capacity. 
In  Tons. 

IRefrigeratiE 
Capacity. 
In  Tons. 

1  Length. 
Feet. 

Width. 
Feet. 

8 

1  Thickness  of 
Iron. 
Inches. 

Number  of 
Coils.  ' 

Pipes  High. 

Feet  LTmg. 

2£a 

|s| 

Total  Feet  o 
Pipe  in 
Condenser. 

Feet  of  Pipe  p 
Ton,  Ice  Mat 
ing  Capacitv 

Feet  of  Pipe  p 
Ton,  Refrige 
ating  Capacit 

5 

10 

.10 

31^ 

6'/2 

3-16 

9 

12 

74 

855 

171. 

85.5 

10 

20 

10 

i*-A 

6J4 

3-16 

20 

12 

7V 

1,900 

190. 

95. 

12J4 

25 

10 

11A 

6|/2 

3-16 

22 

12 

7»/j 

2,090 

167. 

83.6 

15 

30 

10 

8^3 

3-16 

25 

12 

2,375 

151.6 

79.16 

20 

35 

10 

10 

6V4 

3-16 

27 

12 

7j| 

2,565 

128.25 

73.28 

30 

50 

10 

10 

/4 

27 

24 

5,130 

171. 

102.6 

40 

75 

14 

10 

13/4 

% 

27 

24 

ll1^ 

7,695 

191.1 

102.6 

60 

110 

14 

13 

13'/2 

% 

35 

24 

"H 

9,975 

166.25 

90.68 

Aver 

age, 

167. 

89. 

THE  FORECOOLER. 

In  order  to  save  power  and  cooling  water  many 
plants  are  provided  with  supplementary  condensers,  or 
forecoolers,  which  consist  of  a  coil  or  series  of  coils 
through  which  the  compressed  ammonia  is  made  to  pass 
before  it  enters  the  condenser  proper.  The  forecooler  is 
cooled  by  the  spent  or  overflow  water  of  the  condenser. 


132  MECHANICAL   REFRIGERATION. 

If  consisting  of  one  coil,  the  forecooler  should  have  the 
same  size  as  the  discharge  pipe  from  the  compressor ',  if 
consisting  of  a  number  of  coils,  the  manifold  pipe  and 
the  aggregate  area  openings  of  small  pipes  should  equal 
that  of  the  discharge  pipe. 

NOVEL  CONDENSERS. 

Condensers  are  now  also  built,  in  which  the  com- 
pressed gas,  instead  of  entering  a  system  of  coils  im- 
mersed in  water,  enters  a  cylinder  or  shell  while  the 
cooling  water  circulates  through  coils  located  within  the 
cylinder. 

Such  a  condenser  is  described  by  Hendrick  as  to  con- 
sist of  a  heavy  cast  iron  shell  standing  upright  on  a 
channel  iron  frame  ;  it  contains  two  or  more  spiral  coils 
of  1^-inch  extra  heavy  pipe,  the  tails  of  which  project 
through  the  heads  of  the  shell  and  are  united  by  mani- 
folds. The  ammonia  gas,  as  discharged  by  the  com- 
pressor, is  delivered  into  the  shell  at  the  top,  and  as  it 
becomes  liquefied  under  the  influence  of  pressure  and  by 
contact  with  the  coils  through  which  the  condensing 
water  is  circulated  (entering  the  lower  ends  of  the  coil), 
the  liquid  anhydrous  ammonia  collects  in  the  bottom  of 
the  shell,  which  thus  constitutes  the  liquid  anhydrous 
receiver,  and  which  is  provided  with  suitable  level  and 
gauge.  It  will  be  seen  that  in  this  construction  the 
water  is  subdivided  into  two  or  more  separate  and  dis- 
tinct streams,  traveling  through  coils  which  vary  in 
length  from  100  to  175  feet,  according  to  the  size  of  the 
condenser.  This  is  said  to  give  a  much  better  utiliza- 
tion of  the  cold  in  the  water  than  the  ordinary  methods, 
where  the  condensing  coils  are  submerged  in  a  water 
tank,  or  where  the  coils  are  arranged  so  that  the  water 
trickles  over  them ;  in  both  cases  the  water  simply 
traveling  upward  or  downward  ten  to  twenty  feet.  All 
coils  are  continuous  from  end  to  end. 

On  a  similar  principle  brine  coolers  are  made  in 
which  the  brine  circulates  through  systems  of  pipps, 
while  the  ammonia  expands  in  a  shell  or  cylinder  sur- 
rounding the  brine  pipes. 

PURGE  VALVE. 

At  the  highest  point  of  the  condenser,  or  on  the 
discharge  line  next  to  the  condenser,  a  purge  valve 
should  be  provided  for,  to  let  off  permanent  gases. 


THE   AMMONIA  COMPRESSION  SYSTEM.  133 

DUPLEX  OIL  TRAP. 

Frequently  two  oil  traps  are  used,  one  of  which,  gen- 
erally a  larger  one,  is  placed  near  the  machine,  and  the 
other,  the  smaller  one,  near  the  condenser.  When  a 
forecooler  is  used  the  smaller  trap  is  placed  between  it 
and  the  main  condenser.  The  following  table  shows  the 
sizes  of  traps  that  may  be  used  : 


Tons  refrigeration    

2  to  15 

15  to  50 

51  to  60 

61  to  100 

8"X3' 

10"  X  3' 

12"X3' 

12"  X  4' 

Large  trap              

8"X5' 

10"  X  6' 

12"X6' 

12"X8' 

WET  AND  DRY  COMPRESSION. 

If  superheating  is  prevented  by  carrying  liquid  am- 
monia into  the  compressor  to  keep  the  vapor  always 
in  a  saturated  condition,  we  say  that  we  are  working  by 
wet  compression;  and  if,  on  the  other  hand,  the  ammo- 
nia gas  becomes  superheated  during  compression,  we  are 
working  by  what  is  called  dry  compression.  Some  forms 
of  compressors  are  specially  adapted  for  wet  compres- 
sion; others  for  dry  compression. 

Opinions  are  much  divided  as  to  the  relative  merits 
of  these  two  systems  of  compression.  The  theory  shows 
a  gain  of  economy  in  favor  of  wet  compression,  and  the 
practical  results  do  not  contradict  this,  although  the 
difference  is  not  very  great. 

POWER  TO  OPERATE  COMPRESSOR. 

The  power  actually  required  to  operate  a  compressor 
in  order  to  produce  a  ton  of  refrigeration  varies  from 
one  to  two  horse  power,  according  to  size  of  machine, 
other  circumstances  being  equal.  Very  large  machines 
may  be  operated  with  one  horse  power  per  ton  of 
refrigerating  capacity  (in  twenty-four  hours),  but  gen- 
erally one  and  one-third  to  one  and  one-half  horse  powers 
are  required  per  ton  for  machines  of  over  forty  tons  re- 
frigerating capacity.  Machines  from  ten  to  forty  tons 
refrigerating  capacity  will  require  from  one  and  one-half 
to  two  horse  powers  per  ton,  and  still  smaller  machines 
will  require  up  to  two  and  one-half  horse  powers,  and 
sometimes  still  more,  per  ton  of  refrigeration. 

EXPANSION  VALVE. 

This  valve  is  placed  between  the  condenser,  or  rather, 
the  liquid  receiver,  and  the  expansion  or  refrigerating 
coils.  It  is  a  peculiar  valve,  admitting  of  very  fine  adjust- 


134  MECHANICAL  REFRIGERATION. 

ment,  so  as  to  enable  the  engineer  to  admit  the  required 
amount  of  liquid  to  the  expander,  and  no  more. 

EXPANSION  OF  AMMONIA. 

The  expansion  or  volatilization  of  the  liquid  am- 
monia, by  which  the  refrigeration  is  effected,  takes  place 
within  series  or  coils  of  iron  pipes.  These  pipes  may  be 
located  in  the  rooms  to  be  refrigerated  (direct  expansion 
system)  or  they  may  be  placed  in  a  bath  of  salt  brine, 
which,  after  having  been  cooled  in  this  way,  is  circulated 
in  turn  through  the  rooms  to  be  refrigerated,  (indirect 
expansion,  or  brine  system.) 

SIZE  OF  EXPANSION  COILS. 

The  surface  or  the  size  and  length  of  expansion  coils  to 
be  placed  in  the  rooms  to  be  refrigerated,  or  in  the  brine 
tank,  like  nearly  all  the  pipe  work  in  the  refrigerating 
practice,  is  based  on  empirical  rules. 

There  are  no  concise  formulae  on  these  subjects,  as 
exact  experiments  on  the  transmission  of  heat  under 
circumstances  obtaining  in  the  refrigerating  practice  aro 
almost  entirely  wanting. 

Besides  this,  the  conditions  are  very  variable,  owing 
to  the  change  of  pipe  surface  by  atmospherical  condi- 
tions, or  by  the  deposit  of  ice  and  snow  or  by  the  de 
posit  from  the  water,  as  in  case  of  the  condenser,  differ 
ence  in  insulation,  etc.  For  these  reasons  every  manu- 
facturer has  his  own  rules;  and  whatever  is  said  in  this 
compend  on  this  subject  is  abstracted  from  practical  ex- 
perience and  subject  to  modifications  in  individual  cases. 

PIPING  ROOMS. 

The  size  of  pipe  usually  employed  for  piping  rooms 
varies  from  one  to  two  inches,  and  the  length  required 
varies  according  to  circumstances,  more  especially  with 
the  temperature  or  the  back  pressure  of  the  expanding 
ammonia  and  the  temperature  at  which  the  rooms  are  to 
be  held.  If  a  room  is  to  be  held  at  a  temperature  of  34°, 
and  the  temperature  of  the  expanding  ammonia  is  10°, 
it  will  take  only  half  as  much  pipe  to  convey  a  certain 
amount  of  refrigeration  as  it  would  take  if  the  tempera- 
ture of  the  expanding  ammonia  were  at  22°  F. 

In  the  latter  case,  however,  the  machine  works  under 
conditions  far  more  economical,  and  for  this  reason  it  is 
advisable  to  use  the  larger  amount  of  pipe  in  order  to  be 
enabled  to  work  with  a  higher  back  pressure. 


THE  AMMONIA  COMPRESSION  SYSTEM.  135 

TRANSMISSION  PER  SQUARE  FOOT. 

In  allowing  a  difference  of  8°  to  15°  between  the 
temperatures  inside  arid  outside  of  the  pipes  it  is  va- 
riously assumed  that  one  square  foot  of  pipe  surface  will 
convey  2,500  to  4,000  units  of  refrigeration  in  twenty-four 
hours  in  direct  expansion. 

This  figure  nearly  agrees  with  a  transmission  of  heat 
at  the  rate  of  10  B.  T.  units  per  hour,  per  square  foot  sur- 
face, for  each  degree  F.  difference  between  temperature 
inside  and  outside  of  pipe,  in  case  of  direct  expansion.  In 
the  case  of  brine  circulation  the  brine  with  the  same  back 
pressure  has,  of  course,  a  much  higher  temperature  than 
the  ammonia,  and  for  this  reason  the  above  difference  will 
be  much  less,  which  explains  the  fact  that  from  one  and 
one-half  to  two  times  as  much  pipe  is  used  with  brine 
circulation  as  in  direct  expansion. 

If  the  amount  of  piping  is  calculated  on  this  basis, 
allowing  a  refrigeration  of  a  certain  number  of  B.  T. 
units  per  cubic  foot  of  space  to  be  refrigerated,  the  re- 
sult will  generally  fall  short  of  the  piping  required  after 
the  rules  lai'd  down  in  the  following  paragraph.  This  is 
to  be  explained  by  the  fact  that  the  latter  rules  are  given 
on  a  very  liberal  basis  calculated  to  cover  unfavorable 
cases  as  regards  insulation,  size  of  rooms,  etc.,  it  being 
understood  that  any  possible  surplus  in  piping  will  tend 
to  increase  the  efficiency  of  machine.  This  remark  ap- 
plies not  only  to  the  rules  for  piping  in  following  para- 
graph, but  to  rules  on  piping  in  most  cases. 

PRACTICAL  RULE  FOR  PIPING. 

Practically  the  matter,  however,  is  not  often  calcu- 
lated on  this  basis,  but  after  a  rule  of  thumb  it  is  assumed 
(allowing  for  difference  in  insulation  and  size  of  rooms) 
that  about  one  running  foot  of  2-inch  pipe  (direct  expan- 
sion) will  take  care  of  ten  cubic  feet  of  space  in  houses 
which  are  to  be  kept  below  freezing  down  to  a  tempera- 
ture of  10°  F. 

About  one  running  foot  of  2-inch  pipe  will  take  care 
of  forty  cubic  feet  of  space  in  rooms  to  be  kept  at  or 
above  the  freezing  point,  32°  F.,  or  thereabouts. 

About  one  running  foot  of  2-inch  pipe  will  take  care 
of  sixty  cubic  feet  of  space  in  rooms  to  be  kept  at  50°  F., 
and  above,  as  in  the  case  of  ale  storage. 

In  conformity  with  the  remarks  in  preceding  para- 


130 


MECHANICAL  REFRIGERATION. 


graph,  we  take  it  that  these  rules  are  intended  to  cover 
cases  of  rooms  of  50,000  cubic  feet  capacity  and  less, 
poorly  insulated,  and  operated  with  small  differences  in 
temperature.  On  a  similar  basis  it  is  frequently  assumed 
that  one  ton  refrigerating  capacity  will  take  care  of  4,500 
cubic  feet  cold  storage  capacity  to  be  held  at  32°  to  35° 
F.,  and  that  from  260  to  300  feet  of  IM-inch  pipe  will 
properly  distribute  one  ton  of  refrigeration. 

Relating  to  the  question  of  piping  rooms,  condensers 
and  brine  tanks,  it  may  be  understood  once  for  all  that 
there  are  two  sides  to  this  also.  One  contemplates  a  less 
expensive  plant  by  reducing  piping  to  a  minimum  fre- 
quently at  the  expense  of  economical  working.  The 
other  side  aims  at  increasing  the  capacity  by  ample  pipe 
surface,  and  therefore  the  first  outlay  for  a  plant  will  be 
greater,  but  probably  will  pay  better  in  the  end. 

DIMENSIONS  OF  PIPE. 

One  running  foot  of  2-inch  pipe  is  equal  to  1.44  feet 
of  1^-inch  pipe,  and  1.8  feet  of  1-inch  pipe,  as  regards 
surface.  For  similar  comparisons  and  calculations  the 
following  tables  will  be  found  convenient: 

DIMENSIONS  OF  STANDARD  PIPE. 


<£ 

o 

a 

a 

(D«H  g 

vv 

1 

1 

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2 

3 

1 

£^| 

i 

4 

£ 

SL 

1 

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§  » 

"^S 

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0   . 

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o-2  § 

la 

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1 

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gg 

5^1 

•a 

fl 

| 

,af  o 

gj 

15 

fc 

S3 

oQ 
•< 

¥ 

M 
2 

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H 

h  ? 

p 

t-i 

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s* 

G  ®  ^ 

0)  P<O 

I 

2 

N 

m 

a)OU 
£ 

'©"o 

"inT 

In. 

In. 

In. 

In. 

In. 

Ft. 

In. 

In. 

Ft. 

Lbs. 

H 

0.270 

0.405 

0.068 

0.848 

1.272 

9.434 

0.0572 

0.129 

2500 

0.243 

M 

0.364 

0.54 

0.068 

1.144 

1.696 

7.075 

0.1041 

0.229 

1385 

0.421 

0.494 

0.675 

0.091 

1.552 

2.121 

5.657 

0.1916 

0.358 

751.5 

0.562 

l/t 

0.623 

0.84 

0.109 

1.957 

2.652 

4.502 

0.3048 

0.554 

472.4 

0.845 

\ 

0.824 

1.05 

0.113 

2.589 

3.299 

3.637 

0.5333 

0  866 

270.0 

1.126 

1 

1.048 

1.315 

0.134 

~3T292 

4.134 

2.903 

"0.8627 

1.357 

166.0 

1.670 

1.380 

1.66 

0.140 

4.335 

5.215 

2.301 

1.496 

2.164 

96.25 

2.258 

I1/! 

1.611 

1.90 

0.145 

5.061 

5.969 

2.201 

2.038 

2.835 

70.65 

2.694 

2 

2.067 

2.375 

0.154 

6.494 

7.461 

1.611 

3.355 

4.430 

42.36 

3.667 

2'/2 

2.468 

2.875 

0.204 

7.754 

9.032 

1.328 

4.783 

6.491 

30.11 

5.773 

3 

3.067 

3.50 

0.217 

9.636 

10.9C6 

1.091 

7.388 

9.621 

19.49 

7.547 

3.56S 

4.0 

0.226 

11.146 

12.  566 

0.955 

9.837 

12.566 

14.56 

9.055 

4  * 

4.026 

4.5 

0.237 

12.648 

14.137 

0.849 

12.730 

15.904 

11.81 

10-728 

4.508 

5.0 

0.247 

14.153 

15.708 

0.765 

15.939 

19.635 

9.03 

12.492 

5  * 

5.045 

5.563 

0.259 

15.841, 

17.475 

0.629 

19.990 

24.2P9 

7.20 

14.567 

6 

6.065 

6.625 

0.280 

19.054 

20.813 

0.577 

28.889 

34.471 

4.98 

18.764 

7 

7.023 

7.625 

0.301 

2*2.063 

23.954 

0.505 

38.737 

45.663 

3.72 

28.410 

8 

7.982 

8.625 

0  322 

25.076 

27.096 

0.444 

50.039 

58.426 

2.88 

28.348 

9 

9.001 

9.688 

0.344 

>8.277 

30.433 

0.398 

63.633 

73.715 

2.26 

34.677 

10 

10.019 

10.65 

0.336 

31.475 

33.772 

0.355 

78.838 

90.792 

1.80 

40.641 

THE  AMMONIA  COMPRESSION  SYSTEM. 


DIMENSIONS  OF  EXTRA  STRONG  PIPE. 

A  table  giving  dimensions  of  extra  strong  pipe  will 
be  found  in  the  Appendix. 

BRINE  SYSTEM. 

In  the  brine  system  the  expansion  coils,  as  stated,  are 
placed  in  separate  vessels  containing  salt  brine,  which 
is  cooled  down  to  the  desired  degree.  The  brine  so  cooled 
is  then  conducted  through  pipes  located  in  the  rooms  to 
be  refrigerated  by  means  of  force  pumps.  In  ice  making 
the  cells  or  boxes  containing  the  water  for  ice  making  are 
suspended  in  the  brine  tank. 

SIZE  OF  PIPE  IN  BRINE  TANK. 

The  amount  of  piping  allowed  in  brine  tank  is  also 
a  matter  of  practical  experience.  Generally  120  to  150 
running  feet  of  1^-inch  pipe  are  allowed  per  ton  of  re- 
frigerating capacity  (in  24  hours)  in  brine  tank  for  gen- 
eral refrigeration. 

In  case  of  ice  making  250  to  300  running  feet  of  1^- 
inch  pipe  are  allowed  in  brine  tank  per  ton  of  ice  to  be 
manufactured  in  twenty-four  hours. 

TABLE  OF  BRINE  TANKS  AND  COILS. 

The  following  table  shows  the  dimensions  of  some 
brine  tanks  and  coils  for  different  capacities,  expressed  in 
tons  of  refrigerating  capacity  (not  ice  making  capacity). 


Capacity 

In  Tons 

Refrigera- 

tion. 


25  tons.... 
35  "  .... 
60  "  .... 
75  "  .  . 

Average 
per  ton. 


p 


1,664 

2,080 
2,730 

4,785 


®— * 

o 
fa 


2       0<B 

S  _,«  O 


5,016 

6,072 

8,188 

13,963 


200 

173.6 

163.4 


4)    722.9 
180.7 


PIPES  FOR  BRINE  CIRCULATION. 

In  the  case  of  brine  circulation  there  must  be  another 
series  of  coils  in  rooms  to  be  refrigerated,  through  which 
the  brine  circulates,  as  the  brine  does  not  circulate  as 
fast  as  the  ammonia  vapor,  and  for  other  reasons  the 
surface  of  brine  coils  in  storage  rooms  must  be  much 


138 


MECHANICAL  REFRIGERATION. 


larger  than  in  case  of  direct  expansion  under  conditions 
otherwise  similar. 

In  round  figures  it  is  generally  assumed  that  the  area 
of  pipe  surface  in  case  of  brine  circulation  should  be  from 
one  and  one-half  to  two  times  as  large  as  in  case  of  direct 
expansion. 

RULES  FOR  LAYING  PIPES. 

The  pipes  in  storage  rooms  should  be  placed  where 
they  are  least  in  the  way. 

They  should  be  arranged  in  independent  sections  con- 
nected by  manifolds  in  such  a  way  that  each  section  can 
be  shut  out  to  throw  off  the  frost. 

TABLE  FOR  EQUALIZING  PIPES. 

The  size  of  main  pipe  is  given  in  the  column  at  the 
left.  The  number  of  branches  is  given  in  the  line  on  top, 
and  the  proper  size  of  branches  is  given  in  the  body  of 
the  table  on  the  line  of  each  main  and  beneath  the  de- 
sired number  of  branches. 

In  commercial  sizes  the  normal  1^-inch  pipe  is  gen- 
erally over  size;  often  as  large  as  1%.  It  is  safe  to  call  it 
1.3  inches,  and  it  is  so  figured  in  the  table.  Exact  sizes 
are  given  for  branch  pipes.  The  designer  of  the  pipe 
system  can  thus  better  select  the  commercial  sizes  to  be 
used. 


Size  of  Main 
Pipe. 

NUMBER  OP  BRANCHES. 

2 

3 

4 

5 

6 

7 

8 

9 

10 

1     in. 

.758 

.644 

.574 

.525 

.488 

.459 

.435 

.416 

.398 

.985 

.838 

.747 

.683 

.635 

.597 

.556 

.540 

.618 

1/t   " 

1.14 

.967 

.861 

.788 

.733 

.689 

.653 

.623 

.597 

a     " 

1.52 

1.29 

1.15 

1.05 

.977 

.918 

.870 

.830 

.796 

2V4   " 

1.89 

1.61 

1.44 

1.31 

1.22 

1.15 

1.09 

1.09 

.995 

3      " 

2.27 

1.92 

1.72 

1.58 

1.47 

1.38 

1.31 

1.25 

1.19 

3V4    ' 

2  65 

2.26 

2.01 

1.84 

1.71 

1.61 

1.52 

1.45 

1.39 

4       '       ' 

3.03 

2.58 

2.30 

2.10 

1.95 

1.84 

1.74 

1.66 

1.59 

4>4    ' 

3.41 

2.90 

2.58 

2.36 

2.20 

2.07 

1.96 

1.87 

1.79 

5       ' 

3.79 

3.22 

2.87 

2.63 

2.44 

2.30 

2.18 

2.08 

1.99 

6 

4.55 

3.87 

3.45 

3.15 

2.93 

2.75 

2.61 

2.49 

2.39 

7 

5.30 

4.51 

4.02 

3.68 

3.42 

3.21 

3.05 

2.91 

2.79 

8 

6.06 

5.16 

4.59 

4.20 

3.91 

3.67 

3.48 

3.32 

3.18 

9 

6.82 

5.80 

5.17 

4.73 

4.40 

4.13 

3.92 

3.74 

3.58 

10       ' 

7.58 

6.44 

5.74 

5.25 

4.88 

4.59 

4.35 

4.15 

3.98 

12       ' 

9.08 

7.73 

6.89 

6.30 

5.86 

5.51 

5.22 

4.98 

4.78 

In  brine  circulation  the  brine  should  also  be  pumped 
through  series  of  pipes  running  in  the  same  direction, 
and  connected  by  manifolds  to  decrease  friction. 

Further  information  in  regard  to  piping  rooms,  etc., 
will  be  found  in  the  chapters  on  Cold  Storage,  Brewery 
Refrigeration,  etc. 


THE  AMMONIA  COMPRESSION  SYSTEM. 


139 


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III! 

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Diameter  of  Pump  Barrel,  in  Inches. 

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140 


MECHANICAL  REFRIGERATION. 


THE  BRINE  PUMP. 

The  circulation  of  the  refrigerated  brine  through  the 
refrigerating  coils  in  storage  rooms,  etc.,  is  accomplished 
by  the  brine  pump.  The  size  of  the  brine  pump  may  be 
estimated  on  the  basis  that  the  brine  should  not  travel 
faster  than  sixty  feet  per  minute.  The  table  on  opposite 
page  will  be  found  convenient  in  this  connection. 

PREPARING  BRINE. 

The  brine  is  a  solution  of  some  saline  matter  in  water, 
in  order  to  depress  the  freezing  point  of  the  latter.  Gen- 
erally chloride  of  sodium  or  common  salt  is-used  for  this 
purpose.  To  make  the  brine  it  is  well  to  use  a  water  tight 
box,  4X8  feet,  with  perforated  false  bottom  and  com- 
partment at  end,  with  overflow  pipe  for  brine  to  pass  off 
through  a  strainer.  The  salt  is  spread  on  false  bottom, 
and  the  water  fed  in  below  the  false  bottom  as  fast  as  a 
solution  of  the  proper  strength  will  form.  A  wooden  hoe 
or  shovel  may  be  used  for  stirring  to  accelerate  solution. 

TABLE  SHOWING  PROPERTIES  OF  SOLUTION  OF  SALT. 
(Chloride  of  Sodium.) 


• 
bt>>»  . 

ce,o^ 

°£oc 

§3* 

O  .j  O 
ftrto 

o3? 

60     •** 
»«*« 

su- 

Percent 
of  Salt 
Weigh 

en  9?  —  o 

•«H! 
|-3l 

4>  O>o 

ga§ 

»3l2' 
a^ce03 
Man 

*=  fl"J 

1 

if 

'3  a  % 
$•88 

fi^-S 

fa 

fal 
|S| 

1 

0.084 

4 

8.40 

1.007 

0.992 

30.5 

—0.8 

2 

0.169 

8 

8.46 

1.015 

0.984 

29.3 

—1.5 

2.5 

0.212 

10 

8.50 

1.019 

0.980 

28.6 

—1.9 

3 

0.256 

12 

8.53 

1.023 

0.976 

27.8 

—2.3 

3.5 

0.300 

14 

8.56 

1.026 

0.972 

27.1 

—2.7 

4 

0.344 

16 

8.59 

1.030 

0.968 

26.6 

—3.0 

5 

0.433 

20 

8.65 

.037 

0.960 

25.2 

—3.8 

6 

0.523 

24 

8.72 

.045 

0.946 

23.9 

—4.5 

7 

0.617 

28 

8.78 

.053 

0.932 

22.5 

-5.3 

8 

0.708 

32 

8.85 

.061 

0.919 

21.2 

—6.0 

9 

0.802 

36 

8.91 

.068 

0.905 

19.9 

—6.7 

10 

0.897 

40 

8.97 

1.076 

0.892 

18.7 

—7.4 

1.092 

48 

9.10 

1.091 

0.874 

16.0 

—8.9 

15 

1.389 

60 

9.26 

1.115 

0.855 

12.2 

—11.0 

20 

1.928 

80 

9.64 

1.155 

0.829 

6.1 

—14.4 

24 

2.376 

96 

9.90 

1.187 

0.795 

1.2 

—17.1 

25 

2.488 

100 

9.97 

1.196 

0.783 

0.5 

—17.8 

26 

2.610 

104 

10.04 

1.204 

0.771 

—1.1 

—18.4 

STRENGTH  OF  BRINE. 

Generally  speaking,  the  brine  must  contain  sufficient 
salt  to  prevent  its  freezing  at  the  lowest  temperature  in 
freezing  tank,  and  by  referring  to  the  accompanying  table 
one  can  answer  the  question  for  himself  on  this  basis  very 
readily. 


THE   AMMONIA  COMPRESSION   SYSTEM.  141 

To  determine  the  weight  of  one  cubic  foot  of  brine 
multiply  the  values  given  in  column  4  by  7.48. 

To  determine  the  weight  of  salt  to  one  cubic  foot  of 
brine  multiply  the  values  given  in  column  2  by  7.48. 

POINTS  GOVERNING  STRENGTH  OF  BRINE. 

Therefore  if  the  temperature  in  the  freezing  tank 
does  not  go  below  15°  F.,  it  would  be  quite  sufficient  to 
use  a  brine  containing  15  per  cent  of  salt  (salometer  de- 
grees 60),  as  from  the  above  table  it  appears  that  such  a 
solution  does  freeze  below  that  temperature.  On  the  other 
hand,  if  the  temperature  of  freezing  does  not  go  below 
20°  F.,  a  brine  containing  only  10  per  cent  salt  would  be 
sufficient  for  the  same  reason,  etc.  This  table  also  ex- 
plains why  it  would  be  irrational  to  use  stronger  solutions 
of  salt  than  these,  for,  as  we  see  from  the  column  show- 
ing specific  heat,  the  same  grows  smaller  as  the  concen- 
tration of  the  brine  increases,  and  consequently  the 
stronger  the  brine  the  less  heat  a  given  amount  of  brine 
will  be  able  to  convey  between  certain  definite  tempera- 
tures. There  is  another  danger  connected  with  the  use 
of  too  strong,  especially  of  concentrated,  brine  in  refrig- 
eration. Such  brine  may  cause  clogging  of  pipes,  etc.,  on 
account  of  depositing  salt.  This  danger,  however,  is  not 
so  great  as  that  of  having  the  solution  too  thin,  for  while 
it  may  be  concentrated  enough  not  to  freeze  in  the  brine 
tank,  it  may  be  still  too  weak  to  withstand  the  tempera- 
ture obtaining  in  the  expansion  coil,  so  that  a  layer  of 
ice  will  form  around  the  latter  which  interferes  with  the 
prompt  absorption  of  heat  from  the  brine.  For  this  rea- 
son the  surface  of  the  expansion  coils  in  brine  tank 
should  be  inspected  from  time  to  time  to  see  if  any  ice 
has  formed  on  them. 

SIMPLE  DEVICE  FOR  MAKING  BRINE. 

An  ordinary  barrel  with  a  false  bottom  three  inches 
above  the  real  bottom,  perforated  with  j^-inch  holes,  is  a 
practical  contrivance  for  making  brine.  The  space  above 
the  false  bottom  is  filled  with  salt  nearly  to  the  top  of 
the  barrel.  Ordinary  water  is  admitted  below  the  false 
bottom,  and  the  ready  brine  runs  out  at  the  top  through 
a  pipe,  which  is  best  inclosed  in  a  wire  screen  filled  with 
sponges.  The  pipe  carrying  off  the  brine  should  be  about 
larger  than  the  pipe  admitting  the  water. 


142 


MECHANICAL  REFRIGERATION. 
SUBSTITUTE  FOR  SALOMETER. 


In  case  one  is  unable  to  readily  obtain  a  salometer,  a 
Beaume  hydrometer,  or  a  Beck  hydrometer  scale,  both  of 
which  are  in  quite  general  use  for  taking  the  strength  of 
acids,  etc.,  can  be  used  as  well.  Their  degrees  compared 
with  specific  gravity  and  percentage  of  salt  are  shown  in 
the  following  table,  and,  as  will  be  seen,  do  not  differ  so 
very  much  from  the  degrees  of  the  salometer  scale : 


Percentage  of 
Salt  by  Weight. 

Specific 
Gravity. 

Degrees  on 
Beaume's  scale, 
60°  F. 

Degrees  on 
Beck's  scale, 
600  F. 

0 
1 

5 
10 
15 
20 
25 

1.0000 
1.00?2 
1.0362 
1.0733 
1.1114 
1.1511 
1.1923 

0 
1 
5 
10 

8 

23 

0 

1J 

if 

23 

28 

CHLORIDE  OF  CALCIUM. 

Some  engineers  prefer  to  use  chloride  of  calcium  for 
the  preparation  of  brine  in  preference  to  common  salt. 
It  is  higher  in  price  than  the  latter,  but  is  said  to  keep 
the  pipes  cleaner,  causing  less  wear  and  a  better  conduc- 
tion of  heat. 

The  physical  properties  of  the  chloride  of  calcium 
solution,  as  appears  from  the  subjoined  table,  are  quite 
similar  to  those  of  common  salt.  The  freezing  point, 
however,  can  be  depressed  several  degrees  lower  by  the  use 
of  the  former,  and  for  this  reason  the  use  of  chloride  of 
calcium  may  be  advisable  in  such  extreme  cases.  Other- 
wise the  preparation  of  the  solution  of  chloride  of  cal- 
cium is  the  same  as  that  of  ordinary  brine. 

PROPERTIES  OF  SOLUTION  OF  CHLORIDE  OF  CALCIUM. 


Percentage 
by  Weight. 

Specific 
Heat. 

Spec.  Grav. 
at  60°  F. 

Freezg.  Pt. 
degrees  F. 

Freezg.  Pt. 
degs.  Cels. 

1 
5 
10 
15 

20 
25 

0.996 
0.964 
0.896 
0.860 
0.834 
0.790 

1.009 
1.043 
1.087 
1.134 
1.182 
1.234 

31 
27.5 
22 
15 
5 
—8 

—  0.5 
—  2.5 
—  5.6 
—  9.6 
—  14.8 
—22.1 

BRINE  CIRCULATION  VS.   DIRECT  EXPANSION. 

The  principal  reason  why  brine  circulation  is  still 
preferred  by  many  to  direct  expansion,  is  to  be  sought  in 
fear  entertained  with  regard  to  the  escaping  ammonia  in 


THE  AMMONIA  COMPRESSION  SYSTEM.  143 

case  the  pipes  should  leak.  The  danger  from  this  source, 
however,  seems  to  have  been  greatly  exaggerated,  as  but 
few  accidents  of  this  kind  have  been  known,  the  pressure 
in  the  ammonia  pipe  being  generally  not  much  higher 
tnan  in  the  brine  coils. 

Another  advantage  frequently  quoted  in  favor  of 
brine  circulation  is  the  fact  that  comparatively  great 
quantities  of  refrigerated  brine  are  made  and  stored 
ahead,  a  supply  which  can  be  drawn  on  in  case  the  ma- 
chinery should  have  to  be  stopped  for  one  reason  or 
another. 

In  case  of  a  prolonged  stoppage,  refrigerating  brine 
made  by  dissolving  ice  and  salt  together  can  be  circulated 
through  the  brine  pipes,  which  is  also  impracticable  in 
case  of  direct  expansion. 

It  is  also  claimed  that  in  small  plants,  in  case  of  brine 
circulation,  the  general  machinery  might  be  stopped  and 
only  the  brine  pump  be  kept  going  to  dispense  the  sur- 
plus refrigeration  which  had  been  accumulated  in  the 
brine  during  the  day. 

THE  DRYER. 

The  dryer  is  an  attachment  of  more  recent  coinage 
with  which  many  compression  plants  are  provided,  its 
purpose  being  the  drying  of  ammonia  gas.  It  is  a  kind  of 
trap  on  the  suction  pipe  connected  in  such  a  manner  (by 
means  of  a  by-pass)  that  the  gas  can  be  passed  through 
it  when  necessary. 

This  trap  is  provided  with  removable  heads  for  the 
introduction  of  some  moisture  absorbing  substance 
(freshly  burnt  unslaked  lime,  as  a  rule)  and  for  the  with- 
drawal of  the  spent  absorbent. 

LIQUID  TRAP. 

It  is  also  recommended  to  have  an  additional  trap 
between  the  expansion  valve  and  the  expanding  coils. 
The  vaporization  then  takes  place  within  the  chamber  or 
trap,  and  oil  and  other  undesirable  foreign  matter  will  be 
deposited  in  this  trap,  and  will  not  be  carried  over  into 
the  expansion  coils.  The  trap  is  provided  with  a  by -pass, 
so  that  it  can  be  cleaned  without  stoppage. 

If  such  a  trap  can  be  placed  within  the  rooms  to  be 
refrigerated  it  may  be  of  some  advantage ;  but  if  it  has 
to  be  placed  outside,  as  in  the  case  of  brine  circulation, 
much  refrigeration  is  wasted. 


144  MECHANICAL.  REFRIGERATION. 

CHAPTER  V.— ICE  MAKING  AND  STORING. 

SYSTEMS  OF  ICE  MAKING. 

One  of  the  principal  uses  of  mechanical  refrigeration 
is  the  production  of  artificial  ice,  which  is  carried  out 
after  different  methods  or  systems.  The  two  methods 
which  are  most  generally  used  are  the  so-called  can  sys- 
tem and  the  plate  system. 

ICE  MAKING  CAPACITY  OF  PLANT.      . 

From  the  temperature  of  brine  tank  respectively,  the 
temperature  in  expansion  coils  (which  will  be  from  5° 
to  10°  lower),  the  temperature  in  condenser  coil  from  the 
size  of  compressor,  etc.,  the  theoretical  refrigerating 
capacity  of  the  plant  can  be  calculated  as  above  shown, 
making  allowance  for  clearance,  etc.,  as  mentioned. 

The  ice  making  capacity  of  the  plant  is,  of  course, 
much  below  this  theoretical  refrigerating  capacity.  An 
allowance  from  6  to  12  per  cent  loss  due  to  radiation  in 
brine  tank,  pipes,  etc.,  must  be  made  in  the  start,  and  in 
addition  to  that  a  further  allowance  for  the  refrigeration 
of  the  water  from  the  ordinary  temperature  to  that  of 
freezing,  and  for  the  refrigeration  of  the  ice  from  32°  to  the 
temperature  of  the  brine.  For  that  and  other  reasons  it 
may  be  assumed  that  the  ice  making  capacity  of  a  ma- 
chine is  from  40  to  60  per  cent  of  its  theoretical  refriger- 
ating capacity. 

CAN  SYSTEM. 

In  making  ice  by  what  is  called  the  can  system,  the 
water  is  placed  in  cans  or  molds  made  of  galvanized  iron 
of  convenient  shape,  which  are  inserted  in  a  tank  filled 
with  brine,  the  latter  being  kept  cool  by  coils  of  pipe  in 
which  the  expanding  ammonia  circulates.  Temperature 
of  brine  varies  from  10°  to  25°  F.,  15°  F.  being  considered 
favorable. 

SIZE  OF  CANS. 

The  cans  or  molds  for  freezing  vary  in  size  and  shape. 

The  sizes  of  cans  in  most  common  use  are  shown  in  the 

following  table: 

No.  lean,  8^X15X32,  weight  of  cake,  100  Ibs.,  No.  18  Iron. 
"  2    "    8^X16X44,        "  "        150  "        "    18      " 

"  3    "  11     X11X32,        "  "        100  "        "    18      " 

"  4    "  11     X22X32,        "  "        200  "        "     16      " 

"  5    "  11     X22X44,        "  "        300  "        "    15      " 

The  weightis  net.    Allowance  is  made  for  about  5  per 

cent  more  to  allow  for  loss  in  thawing,  etc. 


ICE  MAKING  AND  STORING. 


145 


=3^ 


'IP 

"   § 
^S  ^ 


8g§  8    8    S    8    3  ,,„-. 

Tons 
Ice  Making 
Capacity. 

3 

row—    «      to     •-      *+     *-.—.-.,- 

No.  of  Tanks. 

S£&  £    8    £    SJ    8  StjS 
1  II    1      I      i      i      1   IlJ 

OOO     O       O       O       O»                OOO 

'Length  of 
Tank 
FeetCi  Inches. 

09 

gj 
5; 

CO 

Width  of         S 

8 

f  ??  r  f  r  r  r  m 

•000    O       O       O       0       0    <00t« 

Tank           M 
Feet  &  Inches.   o 

9 

IB" 

-£vJk.^CO        CO        CO        CO        COCOCOCO 
000000     CO       CO       CO       CO       CO    BOOM 

Depth  of         hj' 
Tank             > 
in  Inches.       § 

A 

7? 

co  co  co 

Thickness 
X)f  Plates, 
laches'. 

3 

ssss  8  s  s  sss. 

No.  of  Coils.  ' 

IP 

---  -  -  

Size  of  Pipe, 
Inches. 

a>  ;/> 

0000000       00       00       00       00    05O»O 

Na  of  Pipes  High. 

2,0 

(t>  ® 

1  1  1   1    1    1    1    1   1  1  1 

000    *0       0       0       0       0     00*. 

Length  of  Coils. 

£T 

O  O  O    K>       O       W       OO       O     O  O  4^ 

Total  Feet:  of 
Pipe  in  Tank. 

2.  a 

gMMCO        CO       CO        CO        CO     WtOW 

Feet  of  Pipe  per 
Ton-  Ice  Making 
Capacity. 

|« 

Number  of  Ice 
Molds  in  Tank. 

3> 

Qj?2 

XXXXXXXXXXXXXXXX 

Size  of  Molds 

3 

XxXX  XXXXXXXXX  XXX 

ia  Inches. 

5 

ea 

3* 

Sli888l8is8888§8 

Net  Weight  of 
Ice  from  Each. 

1 

Mold. 

£. 

5>K3>  S     o     o     2     o   co^co 

'*•    '*•  *  *  g  * 

Number  of  Molds 
per  Ton  Ice  Mak- 
ing Capacity. 

P 

^***S*«88 

<Numben  Hours 
for  Freezing 
Each  Mold. 

3 

*        *    *         to 

1 

Remarks. 

146 


MECHANICAL   REFRIGERATION. 


TIME  FOR  FREEZING. 

At  about  14°  to  15°  F.  of  the  brine,  11-inch  ice  will 
take  about  forty-five  to  fifty  hours  to  close,  and  10-inch 
ice  about  thirty-eight  to  forty-four  hours,  and  8-inch 
ice  about  twenty-eight  to  thirty-two  hours.  If  the 
temperature  is  10°  F.  it  will  take  about  20  to  25  por 
cent  less  time,  but  ice  will  be  more  brittle.  Thene 
figures  relating  to  the  time  of  freezing  are  given  on 
the  basis  of  first  rate  conditions  all  around,  which 
are  seldom  if  ever  attained  in  practical  working.  For 
this  reason  estimates  on  the  size  of  brine  tank,  num- 
ber of  cans,  etc.,  are  generally  made  on  the  basis  of  the 
following  freezing  times:  Fifty  to  seventy-two  hours 
for  ice  eleven  inches  thick;  forty  to  sixty  hours  for  ice 
ten  inches  thick,  and  thirty-six  to  fifty  houra  for  ice 
eight  inches  thick.  On  this  basis  twenty  cans  are  re- 
quired  (300-pound  cans,  seventy -two  hours'  freezing  time, 
11-inch  ice)  for  each  ton  of  ice  making  capacity  per  day, 
and  the  room  in  freezing  tank  must  be  in  accordance 
therewith. 

Siebert,  after  a  formula  of  his.  own,  gives  the  follow- 
ing freezing  time  table : 

FREEZING  TIMES  FOR  DIFFERENT  TEMPERATURES  AND  THICK- 
NESSES OF  CAN  ICE. 


Thickn'ss. 

lin. 

2  in, 

Sin. 

4  in.  [5  in. 

6  in. 

7iq. 

8  in. 

9  in. 

10  in. 

11  in. 

12  in. 

45.8 
50.4 
56  0 
63.0 
72.0. 
84.0 
100.0 
120.0 

Temp.  10° 
12° 

$ 

18° 
20° 
22° 
24?r 

0.32 
0.35 
0.39 
0.44 
•0.50 

13 

0,88 

1.28 
1.40 
1.56 
1.75 

2.00 
2.32 
2.80 
3.50 

2.86 
3.15 
3.50 
3.94 
4.50 
5.25 
6.30 
7.86 

S.io!  8.00 
5.60   8.75 
6.22   9.70 
7.0011.0 
S.00'12.6 
9.3014.6 
11.2   17.5 
14.0.21.0 

11.5 
12.6 
14.0 
!5.8 
18.0 
21.0 
25.2 
31.5 

15.6 
17.3 
19.0 
21.5 
24.5 
28.5 

8.1 

20.4 
22.4 
25.0 
28.0 
32.0 
37.3 
44.8 
56.0 

25.8 
28.4 
31.5 
35.6 
40.5 
47.2 
50.7 
71.0 

31.8 
35.0 
39.0 
43.7 
50.0 
58.3 
70.0 
87.6 

38.5 
42.3 
47.0 
53.0 
60.5 
70.5 
84.7 
106.0 

It  will  be  noticed  on  closer  inspection  that  in  this 
table  the  time  for  freezing  different  thicknesses  of  ice  is 
proportional  to  the  square  of  the  thickness.  Thus,  to 
freeze  a  block  ten  inches  thick  takes  100  times  as  long 
as  to  freeze  a  block  of  one  inch  thickness,  and  four  times 
as  long  to  freeze  a  block  of  four  inches  thickness,  than  it 
takes  to  freeze  one  of  two  inches  thickness,  and  so  on. 

PIPE  IN  BRINE  TANK. 


About  250  feet  of  2-inch  or  350  feet  of  IM-inch  pipe, 
or  its  equivalent  according  to  the  temperature  of  brine 
and  capacity  of  machine,  are  generally  used  per  ton  of 
ice  per  twenty-four  hours. 

Less  pipe  is  frequently  used,  even  as  low  as  150  feet 
of  2-inch  pipe,  and  200  feet  of  1^-inch  pipe  per  ton  of 


ICE  MAKING  AND  STORING.  147 

ice  making  capacity  (in  twenty -four  hours),  but  in  that 
case  the  back  pressure  must  be  carried  excessively  low, 
which  duly  increases  the  consumption  of  coal  and  the 
wear  and  tear  of  machinery.  It  is  also  claimed  that 
when  the  agitation  in  brine  tank  is  very  perfect  and  the 
ammonia  expansion  pipes  have  short  runs  (from  header) 
eighty -five  to  100  square  feet  of  pipe  in  brine  tank 
per  ton  of  actual  daily  ice  making  capacity  will  be  suffi- 
cient. These  figures  agree  somewhat  with  the  ones 
given  in  the  foregoing  paragraph. 

ARRANGEMENT  OF  FREEZING  TANK. 

The  size  and  length  of  pipe  in  brine  tank  should  be 
arranged  in  such  a  manner  that  each  row  of  molds  is 
passed  by  an  ammonia  pipe  on  each  side,  preferably  on 
the  wide  side  of  mold.  The  series  of  pipes  in  freezing 
tank  are  connected  by  manifold,  the  liquid  ammonia 
entering  the  manifold  at  the  lower  extremity,  and  the 
vapor  leaving  by  the  suction  manifold  placed  at  the 
higher  extremity  of  the  refrigeration  coils. 

When  working  with  wet  vapor  of  ammonia,  the 
liquid  should  enter  at  the  upper  extremity,  and  leave  for 
compressor  at  lower  extremity  of  refrigeration  coils. 

The  refrigerating  tank  should  be  well  insulated  by 
wainscoting  made  of  matched  boards..  The  space  between 
wainscoting  and  tank  (about  ten  to  eighteen  inches) 
should  be  filled  in  with  sawdust,  cork  or  other  insulating 
material.  It  is  recommended  that  brine  tank  insulation 
should  be  twelve  to  eighteen  inches  thick  on  sides  of 
tank,  and  at  least  twelve  inches  under  the  bottom. 

Brine  tanks  are  made  of  sheet  iron  or  steel,  wood 
and  also  of  cement.  Each  kind  has  its  admirers,  accord- 
ing to  circumstances,  local  and  otherwise.  Tank  steel 
plate  is  said  to  make  the  best  job,  if  properly  built,  and 
will  last  from  ten  to  twelve  years. 

Wooden  tanks  are  built  of  2x4  or  2 x 6-inch  planks, 
according  to  size  of  tank,  and  when  built  that  way  lined 
with  %-inch  matched  flooring.  All  the  2x4  or  the 
matched  flooring  is  laid  and  bedded  in  pure  hot  asphal- 
tum  before  being  nailed  together.  Cedar  or  cypress  and 
hard  yellow  pine  wood  are  recommended  for  brine  tanks. 

Cement  tanks  must  be  made  of  the  best  cement,  and 
thoroughly  hardened  and  dried  and  coated  with  hot 
asphaltum  before  being  used. 


148  MECHANICAL  REFRIGERATION. 

SIZE  OF  BRINE  TANK. 

The  brine  tank  should  be  no  larger  than  is  required 
to  receive  the  molds,  the  refrigeration  coils  and  the  agita- 
tor. Generally  two  inches  space  are  left  between  molds 
and  three  inches  space  where  the  pipes  pass  between 
them.  Three  feet  additional  length  for  tank  are  allowed 
for  agitator.  Otherwise  the  size  of  the  brine  tank 
depends  on  the  size  of  the  mold,  i.  e.,  the  time  which  it 
will  take  to  freeze  the  contents  solid.  If  it  takes  forty- 
eight  hours  to  close  the  cans,  the  freezing  tank  must  hold 
twice  as  much  as  is. expected  to  be  turned  out  in  twenty- 
four  hours. 

THE  BRINE  AGITATOR. 

The  brine  agitator  is  a  little  contrivance  calculated 
to  keep  up  a  steady  motion  of  the  brine;  it  generally  con- 
sists of  a  small  propeller,  driven  by  belt,  which  keeps  up 
a  constant  motion  of  the  brine  from  one  side  of  the  tank 
to  the  other. 

HARVESTING  CAN  ICE. 

The  molds  containing  the  ice  are  withdrawn  from 
the  freezing  tank  in  small  plants  by  "  hand  tackle,"  in 
larger  plants  by  the  power  crane.  The  cans  are  removed 
by  the  crane  to  the  dipping  tank  containing  hot  water, 
called  the  hot  well,  in  which  the  cans  are  suspended  for 
a  short  time,  hoisted  up  again  and  turned  over  on  an 
inclined  plane  or  similar  contrivance  when  the  blocks  of 
ice  drop  out  and  slide  into  the  storage  room.  In  some 
factories  a  sprinkling  device  takes  the  place  of  the  hot 
well. 

PLATE  SYSTEM. 

In  making  ice  after  the  so  called  plate  system,  hollow 
plates  through  which  cold  brine  or  ammonia  can  be  made 
to  circulate  are  immersed  vertically  into  tanks  filled 
with  water,  and  the  ice  forms  gradually  on  both  sides  of 
the  plates,  thus  purifying  itself  of  any  air  or  other 
impurities  on  its  surface,  which  in  the  can  system  con- 
centrate themselves  toward  the  center,  forming  an  im- 
pure core.  For  this  reason  it  is  not  necessary  to  distill 
or  boil  water  which  is  otherwise  p'ure  for  ice  making 
after  the  plate  system  as  it  is  required  in  the  can  system, 
and  hence  a  saving  of  coal  by  the  plate  system.  On  the 
other  hand,  the  latter  system  requires  more  skill  to  man- 
ipulate it  successfully  in  all  its  details,  and  the  plant  is 


ICE   31AKISG   AND   STORING. 


149 


more  expensive  to  install  and  keep  in  repair.  The  com- 
parisons between  the  two  systems  as  to  cost  depend 
largely  on  the  size  of  plants  and  local  conditions.  The 
following  table  of  comparison  showing  the  cost  of  pro- 
duction per  ton  of  the  two  systems  in  first-rate  plants 
will  meet  average  conditions.  It  is  derived  from  Denton, 
and  corrected  after  the  experiences  of  St.  Clair  and 
others. 


Can 
System. 

Plate 
System. 

Harvesting1  unci  storing  Denton 

.11 

.06 

Engineers  and  firemen         

.13 

.12 

Coal  at  $3  60  per  gross  ton 

.43 

.24 

Water  pumped  at  5c.  per  1,000  cubic  feet  
Interest  and  depreciation  at  10  per  cent  

.013 
.246 
.027 

.026 
.327 
.034 

.946 

.807 

SIZE  OF  PLATES. 

The  plates  vary  in  size;  generally  they  are  10X14  feet 
in  area,  and  may  be  made  by  welding  pipe  into  continuous 
coil.  The  spaces  between  the  pipes  are  filled  out  by  metal 
strips,  the  whole  forming  a  solid  plate. 

TIME  FOR  FREEZING. 

The  freezing  on  the  plates  to  form  ice  of  a  thickness 
of  about  twelve  to  fourteen  inches  takes  from  nine  to 
fourteen  days,  forming  cakes  of  ice  weighing  several 
tons. 

HARVESTING  PLATE  ICE. 

When  the  ice  on  the  plate  has  become  thick  enough, 
hot  ammonia  taken  from  the  system  before  it  enters  the 
condenser  is  let  into  the  plate  coil,  where  it  loosens  the 
ice  from  the  metal  in  a  few  minutes.  The  cake  is  then 
split,  and  grooves  cut  by  circular  saws  or  hand  plows 
enable  the  splitting  of  the  whole  cake  into  pieces  of  desired 
size,  ready  for  market. 

STORAGE  OF  MANUFACTURED  ICE. 

The  question  whether  it  is  more  economical  to  shut 
down  the  ice  plant  during  the  winter  and  have  a  plant  of 
sufficient  size  to  supply  the  summer  demand,  or  to  store 
ice  during  the  winter  months  and  get  along  with  a 
smaller  plant,  appears  now  to  be  decided  in  favor  of  the 
latter  system,  at  least  under  generally  prevailing  condi- 
tions. 


150  MECHANICAL  REFRIGERATION. 

ICE  FOR  STORAGE. 

The  best,  clear,  solid  ice,  without  any  core  of  any 
kind,  is  also  the  best  for  storage.  Some  insist  that  ice 
for  storage  should  not  be  made  at  temperatures  higher 
than  10°  to  14°  in  brine  tank,  but  where  the  storage  or 
ante-room  is  kept  cool,  this  is  hardly  required. 

CONSTRUCTION  OF  STORAGE  HOUSES. 

Storage  houses  for  manufactured  ice  are  built  on 
the  same  principle  as  storage  houses  for  natural  ice. 
Efficient  insulation  is  the  principal  consideration.  The 
house  should  be  built  as  nearly  square  as  possible,  the 
roof  should  have  a  good  pitch,  and  both  gable  ends,  as  well 
as  the  top,  should  be  ventilated.  The  escape  of  cold  air,  as 
well  as  the  ingress  of  warm  air  at  the  bottom  should  be  well 
guarded  against.  A  plain  house  may  be  built  of  frame 
with  2X8  studdings,  lined  inside  with  P.  &  B.  building 
paper  and  1-inch  boards.  The  outside  to  be  lined  with 
one  thickness  of  boards  and  two-ply  paper,  the  8-inch 
space  between  being  filled  with  tan  bark.  The  outside 
has  a  4-inch  air  space;  is  then  lined  outside  with  tongued 
and  grooved  weather  boarding.  The  roof  is  covered  with 
paper,  and.  has  an  8-foot  ventilator  on  top. 

ANTE-ROOM. 

Storage  houses  for  manufactured  ice  should  be  pro- 
vided with  an  ante-room  holding  some  fifty  tons  of  ice 
and  over,  so  as  to  obviate  the  frequent  opening  of  the 
storehouse  proper.  This  ante-room  should  be  kept  cool 
by  pipes  .supplied  with  refrigerated  brine  or  ammonia 
from  the  machine. 

Fifty  cubic  feet  of  ice  as  usually  stored  will  equal 
about  one  ton  of  ice, 

REFRIGERATING  ICE  HOUSES. 

In  order  to  keep  the  ice  intact  in  storage  rooms,  etc., 
the  same  must  be  refrigerated  by  artificial  means.  Gen- 
erally a  brine  or  direct  expansion  coil  is  used  for  that 
purpose. 

The  refrigeration  and  size  of  coils  required  may  be 
calculated  after  the  rules  given  above  and  further  on 
under  "Cold  Storage."  For  rough  estimations  it  is  as- 
sumed that  such  rooms  require  about  ten  to  sixteen  B. 
T.  U.  refrigeration  per  cubic  feet  contents  for  twenty- 
four  hours. 


ICE  MAKING  AND  STORING.  151 

« 

About  one  foot  of  2-inch  pipe  (or  its  equivalent  in 
other  size  pipe)  per  fourteen  to  twenty  cubic  feet  of  space 
are  frequently  allowed  in  ice  storage  houses  for  direct 
expansion,  and  about  one-half  to  one-third  more  for 
brine  circulation. 

The  pipes  should  be  located  on  the  ceiling  of  the 
ice  storage  house.  It  is  also  important  that  the  house  is 
well  ventilated  from  the  highest  point,  and  thoroughly 
drained  to  prevent  any  accumulation  of  moisture  below 
the  bed  of  ice.  A  foundation  bed  of  one  and  a  half  to  two 
feet  of  cinders  greatly  assists  the  drainage  of  the  house. 
Ice  storage  houses  should  be  painted  white,  but  not  with 
white  lead  or  zinc,  as  a  mineral  paint,  like  barytes  or 
patent  white,  will  emit  less  heat.  9 

PACKING  ICE. 

Different  methods  obtain  in  packing  ice  into  stor- 
age houses. 

Some  place  the  blocks  on  edge,  and  as  closely  to- 
gether as  possible,  and  place  the  other  blocks  on  top 
exactly  over  each  other  (no  breaking  of  joints).  Between 
the  times  of  storing  the  ice  is  covered  with  dry  sawdust 
or  soft  (not  hard)  wood  planer  shavings.  The  top  layer 
is  always  covered  with  dry  sawdust  or  shavings. 

Others  recommend  strongly  the  use  of  ^-inch  strips 
between  layers  of  manufactured  ice  in  the.  storehouse,  the 
cakes  being  separated,  top,  side  and  bottom,  from  all 
others  in  the  house. 

Instead  of  sawdust,  etc.,  rice  chaff  is  used  in  the 
south,  and  it  can  be  dried  and  re-used.  Straw  or  hay  is 
also  used  in  places.  When  sawdust  is  used  in  packing 
ice  the  layer  must  not  be  too  thick,  as  this  would  create 
heat  in  itself. 

It  is  also  recommended  to  store  the  ice  with  alternate 
ends  touching  and  alternately  from  one  and  a  half  to  two 
inches  apart,  somewhat  similar  to  a  collapsed  worm 
fence,  alternating  on  each  row.  This  prevents  the  ice 
from  freezing  together  solidly,  so  that  it  may  be  easily 
separated.  The  cakes  should  not  be  parallel  with  each 
other,  and  should  never  be  stored  unless  the  temperature 
is  at,  or  below,  the  freezing  point.  Prairie  hay  is  the 
best  for  covering ;  oat  or  wheat  is  next  best,  with  saw- 
dust last.  Six  inches  of  hay  should  be  used  between 
the  ice  and  the  wall,  well  packed.  There  should  be  no 
covering  used  until  the  house  is  filled.  Use  hay  first, 


OFTH€ 

UNIVERSITY  ) 


152  MECHANICAL  REFRIGERATION. 

secondly  straw,  and  last  sawdust  if  no  hay  can  be  got. 
In  warmer  climates  ice  should  be  stored  and  covered 
immediately  on  coming  from  the  tank  at  a  very  low 
temperature,  say  12°  or  15°. 

SHRINKAGE  OF  ICE. 

In  an  ice  storage  house  without  artificial  refrigera- 
tion the  average  shrinkage  from  January  to  July  will  be 
about  one-tenth  pound  of  ice  for  every  twenty-four 
hours  for  every  square  foot  of  wall  surface.  In  round 
numbers  it  may  amount  to  from  6  to  10  per  cent  of  the  ice 
stored  in  the  six  months  mentioned. 

HEAT  CONDUCTING  POWER  OF  ICE. 

From  an  interpretation  of  practical  data,  it  appears 
that  about  ten  B.  f.  U.  of  heat  will  pass  through  a 
square  foot  of  ice  one  inch  thick  in  one  hour  for  every 
degree  Fahrenheit  difference  between  the  temperatures 
on  either  side  of  the  ice  sheet. 

WITHDRAWING   AND   SHIPPING  ICE. 

In  withdrawing  ice  from  storage  care  should  be  taken 
that  the  water  from  the  top  does  not  get  down  to  the  ice 
below.  Where  there  is  an  ante-room  the  same  is  filled 
from  time  to  time  from  the  main  storage  room,  to  with- 
draw from  as  occasion  requires.  For  the  shipment  of  ice 
in  large  quantities,  in  cars,  boats,  etc.,  it  is  packed  the 
same  as  for  storage.  Small  quantities  of  ice  are  fre- 
quently shipped  by  express,  etc.,  in  bags  well  packed  with 
sawdust  or  the  like. 

In  withdrawing  ice  from  storage  houses  (''breaking 
out ")  skilled  labor  is  required,  and  besides  this  the  proper 
tools,  viz.:  Two  breaking  out  bars,  one  for  bottom  and  one 
for  side  breaking;  otherwise  much  ice  will  be  broken 
and  wasted. 

The  small  pieces  of  ice  remaining  on  top  layer,  as  well 
as  any  wet  shavings  or  other  material,  should  be  removed 
each  time  when  ice  is  taken  from  the  house. 

SELLING  OF  ICE/ 

The  selling  and  delivery  of  ice  is  generally  done  by 
the  coupon  system. 

It  is  a  system  of  keeping  an  accurate  account  with 
each  customer  of  the  delivery  of  and  the  payment  for  ice 
by  means  of  a  small  book  containing  coupons,  which  in 
the  aggregate  equal  500  or  1,000  or  more  pounds  of  ice, 
each  coupon  representing  the  number  of  pounds  of  ice 
taken  by  the  customer  every  time  ice  is  delivered. 


ICE  MAKING  AND  STORING,  153 

These  books  are  used  in  the  delivery  of  ice  in  like 
manner  as  mileage  books  or  tickets  are  used  on  the  rail- 
road. A  certain  number  of  coupons  are  printed  on  each 
page,  each  coupon  being  separated  from  the  others  by 
perforation,  so  that  they  are  easily  detached  and  taken 
up  by  the  driver  when  ice  is  delivered. 

Such  books  are  each  supplied  with  a  receipt  or  due 
bill,  so  that  if  the  customer  purchases  his  ice  on  credit 
all  that  is  necessary  for  the  dealer  to  do  is  to  have  the 
customer  sign  the  receipt  or  due  bill  and  hand  him  the 
book  containing  coupons  equal  in  the  aggregate  to  the 
number  of  pounds  of  ice  set  forth  in  the  receipt  or  due  bill. 
The  dealer  then  has  the  receipt  or  due  bill,  and  the  cus- 
tomer has  the  book  of  coupons.  The  only  entry  which 
the  dealer  has  to  enter  against  such  purchaser  in  his 
books  is  to  charge  him  with  coupon  book  number,  as  per 
number  on  book,  to  the  amount  of  500,  1,000  or  more 
pounds  of  ice,  as  the  value  of  the  book  so  delivered  may  be. 
The  driver  then  takes  up  the  coupons  as  he  delivers  the 
ice  from  day  to  day. 

WEIGHT  AND  VOLUME  OF  ICE. 

One  cubic  foot  of  ice  weighs  fifty-seven  and  one-half 
pounds  at  32°. 

One  cubic  foot  of  water  frozen  at  323  makes  1.0855 
cubic  feet  of  ice,  the  expansion  being  8%  per  cent  by 
freezing. 

One  cubic  foot  of  pure  water  at  the  point  of  its 
greatest  density,  39°  F.,  weighs  62.43  pounds. 

HANDLING  OF  ICE. 

The  handling  of  ice  during  transit  and  delivery  to 
the  retail  customer  is  a  matter  to  which  all  possible 
attention  should  be  given,  especially  by  the  dealers  in 
manufactured  ice,  in  order  to  reap  the  full  benefit  for 
the  expense  and  care  bestowed  by  them  on  the  making 
of  a  pure  article.  The  wagons  in  which  the  water  is 
delivered  should  be  in  a  clean,  sanitary  condition  in  fact 
as  well  as  in  appearance.  The  men  in  charge  of  them 
should  not  walk  around  in  the  wagons  with  muddy 
boots.  The  ice  should  not  be  slid  on  dirty  sidewalks, 
and  then  be  washed  off  with  water  from  the  same 
bucket  with  which  the  horses  are  watered.  These  things, 
although  they  may  seem  to  be  of  little  consequence,  are 
nevertheless  watched  and  commented  on,  and  go  far  to 


154  MECHANICAL  RE  FEDERATION. 

discredit  the  just  claims  made  by  the  manufacturer  of 
ice  in  favor  of  his  product.  The  same  remarks  hold 
good  for  the  shipment  of  ice  in  railroad  cars.  They 
should  also  be  properly  cleaned,  and  in  case  any  cover- 
ing material  is  needed,  it  should  be  selected  with  the 
same  care  as  that  for  the  covering  of  ice  in  storage  at 
the  factory. 

COST  OF  I€E. 

The  cost  to  manufacture  and  to  keep  in  readiness 
for  shipping  a  ton  of  ice  varies  greatly  with  circum- 
stances, notably  the  price  of  fuel,  the  kind  of  water,  the 
regularity  with  which  the  plant  is  operated,  etc.  The 
cost,  therefore,  is  all  the  way  from  $1  to  $2.50  per  ton. 

It  is  also  found  that  one  pound  of  average  coal  will 
make  from  five  to  ten  pounds  of  ice,  according  to  cir- 
cumstances, and  that  from  three  to  seven  gallons  of 
water  are  required  per.  minute  to  make  one  ton  of  ice  in 
twenty- four  hours. 

COST  OF  MAKING  ICE. 

The  cost  of  making  ice  varies  also  considerably  with 
the  size  of  plant.  Of  a  model  plant  producing  about 
100  tons  of  ice  per  twenty-four  hours  the  following  data 
of  daily  expense  are  recorded,  and  we  consider  them 
very  low : 

Chief  engineer $  5.00 

Assistant  engineer 6.00 

Firemen 4.00 

Helpers 5.00 

Icepullers 9.00 

Expenses 12.00 

Coal,  at  about  $1.10  per  ton 18.00 

Delivering  at  50c  per  ton  (wholesale  delivery) 50.00 

Repairs,  etc 3.00 

Insurance,  taxes,  etc 6.00 

Interest  on  capital 20.55 

Total  for  100  tons  of  ice $138.55 

Calculating  on  the  smaller  production  of  twenty 
tons  in  twelve  or  twenty-four  hours  we  obtain  the  fol- 
lowing figures  : 

Twenty  tons  Twenty  tons 

in  12  hours.  in  24  hours. 

Engineer $2.50  $5.00 

Fireman 1.50  3.00 

Watchman ~     1.00          

Coal 3.00  3.00 

Repairs 50  .50 

Total  for  20  tons  of  ice. . .  $8.50  $11.50 


Average  per  ton 42. Sets      57. Sets. 


ICE  MAKING  AND  STOKING. 


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per  day. 


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*4)  illiU.  APICAL 

SKATING    RINKS. 

Artificial  ice  is  also  used  for  skating  rinks  to  be 
operated  all  the  year  round.  The  amount  of  refrigera- 
tion, piping,  etc.,  required  for  such  installations  depends 
largely  on  local  conditions  and  other  circumstances. 

A  skating  rink  in  Paris  7,700  square  feet  has  15,000 
feet  1-inch  pipe,  and  the  refrigerating  machine  requires 
a  100-horse  power  engine. 

A  skating  rink  in  San  Francisco,  10,000  square  feet,  is 
operated  by  machine  of  sixty  tons  refrigerating  capacity. 

The  skating  floor  at  the  Shenley  Park  Casino  in 
Pittsburg  is  constructed  as  follows:  It  consists  of  a 
3-inch  plank  floor  covered  with  two  thicknesses  of 
impervious  paper;  the  second  floor  likewise  covered, 
leaving  an  air  space  below.  About  80,000  pounds  of 
coke  breeze,  or  about  ten  inches  in  thickness,  was  placed 
on  the  last  named  floor,  the  whole  surmounted  by 
3  x  6-inch  yellow  pine  decking,  carefully  spiked  down 
and  joints  calked,  the  whole  finished  with  a  heavy  coat 
of  brewer's  pitch,  this  preventing  any  dampness  from 
reaching  the  insulation.  Nearly  300,000  feet  of  lumber 
were  used  for  this  structure,  the  rink  being  70  x  225 
feet,  or  about  16,000  square  feet.  On  the  top  of  the 
floor,  with  the  ends  extending  through  the  two  ends  of 
tank,  which  are  rendered  water  tight,  are  72,000  feet  of 
1-inch  extra  heavy  pipe,  and  they  are  simply  straight 
pipes  228  feet  long,  connected  at  each  end  by  a  manifold. 
They  are  operated  by  direct  expansion.  This  rink  will, 
in  case  of  a  rush,  accommodate  1,100  people,  and  one 
having  one-quarter  of  its  surface  would  probably  suffice 
for  a  patronage  of  200  people.  The  refrigerating  ma- 
chine used  to  operate  this  plant  has  a  refrigerating 
capacity  of  about  160  tons. 

QUALITY  OF  ICE. 

The  keen  competition  between  manufactured  and 
natural  ice  has  brought  up  a  number  of  questions  touch- 
ing the  relative  merits  of  these  articles.  Although  it  is 
quite  generally  conceded  that  ice  made  from  distilled 
water  is  in  every  respect  purer  and'more  healthful  than 
natural  ice,  still  there  are  claims  to  the  contrary,  some 
claiming  that  natural  ice  will  last  longer,  others  that 
distillation  takes  the  life  out  of  the  water  and  ice,  etc. 
As  far  as  the  keeping  is  concerned,  there  is  no  difference 
if  the  blocks  are  wholly  frozen  without  holes  or  cracks 


ICE  MAKING   AND   STORING.  157 

in  them;  and  as  to  the  life  in  manufactured  ice,  it  is  cer- 
tainly one  of  its  advantages  that  all  bacterial  life  is 
killed  in  the  same. 

WATER  FOR  ICE  MAKING. 

Expressed  broadly,  water  that  is  fit  for  drinking  pur- 
poses is  fit  for  ice  making,  but  while  for  drinking  pur- 
poses a  moderate  amount  of  air  and  mineral  matter  in 
the  water  is  more  or  less  desirable,  for  ice  making  the 
absence  of  both  is  necessary  if  the  ice  is  to  be  clear 

But  even  if  a  natural  ice  from  a  certain  source  is 
apparently  or  temporarily  free  from  pathogenic  (disease) 
bacteria,  it  may  nevertheless  be  suspected  of  possible  or 
future  contamination  if  its  analysis  indicates  contamin- 
ation with  sewage  or  other  waste  matter.  This  is  to  be 
suspected  when  the  ice  or  the  water  melted  from  the 
same  contains  an  excess  of  ammonia,  especially  album- 
inoid ammonia,  of  nitrates  and  of  chlorides.  In  order 
to  give  expression  to  this  condition  of  things,  many 
municipalities  have  special  laws  defining  the  purity  re- 
quired for  marketable  ice.  The  corresponding  ordinance 
in  the  city  of  Chicago  demands  that :  "  All  ice  to  be  de- 
livered within  the  city  of  Chicago  for  domestic  use  shall 
be  pure  and  healthful  ice,  and  is  hereby  defined  to  be  ice 
which,  upon  chemical  and  bacteriological  examination, 
shall  be  found  to  be  free  from  nitrates. and  pathogenic 
bacteria,  and  to  contain  no  more  than  nine-thousandths 
of  one  part  of  free  ammonia  and  nine-thousandths  of  one 
part  of  albuminoid  ammonia  in  100,000  parts  of  water." 

CLEAR  ICE. 

Although  ice  that  is  impure  may  be  clear,  and  ice 
which  is  practically  pure  may  be  cloudy  or  milky,  clear 
ice  is  nevertheless  desirable,  and  generally  called  for, 
While  many  natural  waters  will  furnish  clear  ice  after 
the  plate  system,  the  can  system  always  requires  boiling, 
and  generally  previous  distillation  and  reboiling  of  the 
water  in  order  to  furnish  clear  ice.  ( It  sometimes  happens 
that  the  ice  of  some  cans  is  white  and  milky,  while  that 
of  others  is  clear.  This  is  generally  due  to  a  leak  in  the 
cans  yielding  the  milky  ice,  whereby  brine  enters  the 
same.  It  may  be  readily  detected  by  the  taste  of  the  ice. ) 

BOILING  OF   WATER. 

In  case  a  natural  water  is  almost  free  from  mineral 
matter  (or  if  the  same  consists  chiefly  of  carbonates  of 


158  MECHANICAL  REFRIGERATION. 

lime  and  magnesia),  and  contains  only  suspended  matter 
and  air  in  solution,  it  may  be  rendered  fit  for  clear  ice 
making  by  vigorous  boiling,  either  with  or  without  the 
assistance  of  a  vacuum,  and  with  or  without  subsequent 
filtration,  as  the  case  may  require. 

DISTILLED  WATER. 

In  order  to  save  a  vast  amount  of  fuel,  40  per  cent 
and  upward,  the  exhaust  steam  from  the  engine  is  gen- 
erally used  to  supply  the  distilled  water  as  far  as  it  goes, 
and  a  deficiency  is  supplied  directly  from  steam  boiler. 

The  impurities,  such  as  grease,  etc.,  carried  by  the 
exhaust  steam,  are  removed  by  a  so-called  steam  filter, 
and  then  the  vapors  are  passed  through  a  condenser  con- 
structed on  the  same  principles  as  the  ammonia  con- 
denser. The  condenser  may  be  submerged  in  water  or 
be  an  atmospherical  or  open  air  condenser.  For  cooling, 
the  overflow  water  from  the  ammonia  condenser  is  used 
in  all  cases. 

AMOUNT  OF  COOLING  WATER. 

If  960  B.  T.  U.  is  the  latent  heat  of  •  steam,  and  the 
temperature  of  the  cooling  water  when  it  reaches  the 
condenser  is  1 t,  and  when  it  leaves  the  condenser  is  t, 
the  theoretical  amount  of  cooling  water,  P,  in  pounds 
required  per  ton  of  distilled  water  is — 
p  __  2000  X  960 

t-t, 

To  this  from  2  to  20  per  cent  should  be  added  for  loss, 
etc.,  according  to  size  of  plant. 

SIZE  OF  CONDENSER. 

If  t  is  the  mean  temperature  of  the  cooling  water, 
that  is,  the  average  between  the  temperature  of  the 
water  entering  and  leaving  the  condenser,  and  if  tt  is 
the  average  temperature  in  the  condenser  (presumably 
about  210°  F.)t  then  the  number  of  square  feet  condenser 
surface,  <S,  per  ton  of  water  in  twenty-four  hours  is 
found  after  the  rule— 

„  2000  X  960 

(tt  —  *)nX24 

n  being  the  number  of  B.  T.  U.  transferred  by  one  square 
foot  surface  of  iron  pipe  for  each  degree  F.  difference 
in  one  hour,  steam  being  on  one  side  and  water  on  the 
other.  For  practical  calculations  fifty  feet  of  1%-inch 
pipe  are  allowed  in  a  steam  condenser  for  each  ton  of  ice 
produced  in  twenty-four  hours. 


ICE  MAKING  AND  STORING.  159 

This  is  equivalent  to  about  twenty-two  square  feet 
of  condenser  surface  per  ton  of  ice  made  in  twenty-four 
hours.  If  we  assume  that  this  amount  of  surface  is  cal- 
culated to  prove  fully  sufficient  even  if  the  cooling  water 
has  a  temperature  of  130°  F.  (the  range  temperature  in 


__  i  on 

this  case  being  212  —  -p-  =  40)  we  find  n  =  100  or 

very  nearly  that. 

From  experiments  quoted  on  page  27  it  appears  that  n 
varies  from  200  to  500  units,  and  is  still  more,  nearly  twice 
that,  in  case  of  brass  or  copper  pipe  which  is  frequently 
used  for  steam  condensers  in  distilling  apparatus.  We 
may  assume,  therefore,  that  n  =  100  will  give  ample  con- 
densing in  extreme  cases,  and  also  allow  for  decrease  in 
the  heat  transmitting  power  of  iron  pipes  on  account  of 
oxidation,  incrustation  and  the  like. 

The  condenser  should  be  provided  with  an  efficient 
gas  and  air  collector. 

In  case  the  natural  water  is  very  impure,  a  filtration 
of  the  same  before  it  enters  the  steam  boiler  is  very  ad- 
visable and  frequently  resorted  to. 

Various  kinds  of  niters  are  used,  sponge,  charcoal 
and  sand  filters  most  generally;  in  exceptional  cases 
boneblack  filters  are  used  also.  In  case  the  water  con- 
tains much  dissolved  organic  matter,  filtering  with  ad- 
dition of  alum  is  found  very  advantageous  in  many  cases. 

REBOILING  AND  FILTERING  WATER. 

The  condensed  distilled  water  contains  air  in  solution, 
and  sometimes  also  certain  other  volatile  substances, 
possessing  more  or  less  objectionable  flavors.  To  free  it 
from  both,  the  water  is  subjected  to  vigorous  reboiling  in 
a  separate  tank.  Impurities  thrown  to  the  surface  are 
skimmed  off. 

The  reboiling  of  the  water  must  not  be  done  by  live 
steam  (no  perforated  steam  coil)  if  the  water  has  natur- 
ally a  bad  smell. 

As  a  still  further  means  of  purification  a  charcoal  or 
other  filter  is  used,  through  which  the  water  passes  after 
reboiling. 

COOLING  THE  DISTILLED  WATER. 

The  filtered  and  boiled  distilled  water  is  now  passed 
through  a  condenser  coil  over  which  cold  water  (water 
which  is  afterward  used  on  ammonia  condenser)  passes, 
and  after  it  is  cooled  down  here  as  much  as  practicable, 


160  MECHANICAL   REFRIGERATION. 

it  runs  to  the  storage  tank  which  is  generally  provided 
with  a  direct  expansion  ammonia  coil  to  reduce  the  tem- 
perature of  the  water  as  near  to  the  freezing  point  as 
possible.  From  the  storage  tank  the  freezing  cans  are 
filled  as  required. 

INTERMEDIATE  FILTER. 

Frequently  another  water  filter  is  placed  between  the 
water  cooler  and  the  storage  tank. 

DIMENSIONS  OF  DISTILLING  PLANT. 

As  is  the  case  with  most  other  appliances  in  the  re- 
frigerating practice,  the  dimensions  of  the  different  parts 
of  a  distilling  plant  vary  considerable  with  different 
manufacturers.  For  superficial  guidance  we  will  quote 
one  or  two  examples. 

TEN-TON  DISTILLING  PLANT. 

Open  air  condenser  consisting  of  ninety-six  pipes,  each 
five  feet  long  and  one  and  one-quarter  inch  diameter. 

Reboiler  four  feet  diameter,  three  feet  high,  con- 
taining steam  coil  of  about  sixty  feet  ^-inch  pipe. 

Intermediate  cooler  to  bring  temperature  of  reboiled 
water  to  about  80°  consists  of  eighteen  pieces  l^-inch 
pipe,  each  twelve  feet  long. 

Charcoal  filter  thirty  inches  in  diameter  and  seven 
feet  high.  Layer  of  charcoal  five  feet  high. 

Cooling  and  storage  tank  three  feet  diameter  and 
seven  feet  high,  contains  250  feet  1^-inch  pipe  for  direct 
ammonia  circulation. 

In  the  installation  of  a  plant  it  is  generally  prudent 
to  expect  an  increase  in  the  production,  and  on  this  basis 
the  above  dimensions  might  well  apply  to  smaller  plants, 
say  downward  to  five  tons. 

THIRTY-TON  PLANT. 

Steam  filter  three  feet  diameter,  seven  feet  high  with 
five  consecutive  wire  screens,  sixteen  meshes  per  inch. 

Surface  condenser  containing  100  pieces  1-inch  brass 
pipe,  each  four  and  a  half  feet  long.  (On  this  basis  and  on 
the  assumption  made  in  the  discussion  of  the  last  formula  n 
would  be  equal  to  about  400  units  for  brass,  which  nearly  agrees 
with  the  experiments  quoted  on  page  26.) 

Reboiler  twenty-four  inches  diameter,  six  feet  high, 
containing  four  feet  steam  pipe  ten  inches  in  diameter. 

Intermediate  cooler,  thirty-two  pieces  of  2-inch  pipe, 
each  seventeen  and  a  half  feet  long. 


ICE  MAKING  AND   STORING.  161 

Two  charcoal  filters,  each  three  feet  diameter,  seven 
feet  high.  Layer  of  charcoal  five  and  a  half  feet  high. 

Cooling  and  storage  tank  six  and  a  half  feet  diameter 
and  eight  feet  high,  containing  750  feet  1^-inch  pipe  for 
direct  ammonia  expansion. 

Sand  filter  two  feet  diameter,  four  feet  high. 

THE  SKIMMER. 

The  skimmer  is  a  contrivance  which  is  arranged  in 
many  plants  between  the  reboiler  and  the  intermediate 
cooler,  to  skim  off  oil  or  any  other  light  impurities  which 
may  float  on  the  water.  It  is  a  small  cylindrical  vessel 
with  an  overflow  at  the  top  and  connected  to  the  reboiler 
with  a  straight  pipe  on  the  one  side,  and  on  the  other 
with  the  intermediate  cooling  coil.  The  flow  of  the  dis- 
tilled water  to  the  latter  coil  is  so  regulated  that  a  small 
amount  of  water  will  always  overflow  from  the  skimmer, 
taking  with  it  the  impurities.  Sometimes  the  skimmer  is 
provided  with  a  steam  coil  to  keep  the  water  boiling, 
thus  facilitating  the  rising  to  the  surface  of  impurities. 

BRINE   CIRCULATION. 

Among  the  other  devices  used  for  brine  circulation 
besides  propeller  wheels,  paddles,  etc.,  we  mention  the 
pump — preferably  a  centrifugal  pump  with  a  system  of 
brine  suction  and  discharge  pipes  located  inside  of  the 
freezing  tank,  to  take  out  the  suction  and  return  the 
discharge  brine  at  regular  intervals  of  space  throughout 
the  length  and  breadth  of  the  tank,  so  that  every  spot 
between  the  cans  is  drawn  into  the  circulation. 

ECONOMIZING  FUEL. 

As  much  of  the  overflow  water  from  the  steam  con- 
denser as  may  be  needed  for  boiler  feeding  should  be 
made  to  pass  through  a  feed  water  heater  located  be- 
tween the  steam  filter  or  oil  separator  and  the  condenser. 
Through  this  heater  the  hot  steam  passes  first,  to  make 
the  feed  water  as  hot  as  possible. 

ARRANGEMENT  OF  PLANT. 

It  is  essential  that  the  whole  of  the  distilling  ap- 
paratus is  kept  clean,  sweet  and  free  from  iron  rust;  for 
these  reasons  the  plant  should  be  so  arranged  that  all 
tanks,  pipes,  etc.,  which  contain  or  conduct  the  distilled 
water  are  constantly  filled  with  the  same. 

The  plant  should  be  cleaned  as  often  as  necessary  by 
steaming  the  same  out. 


162  MECHANICAL  REFRIGERATION. 

DEFECTS  OF  ICE. 

Water  which  has  gone  through  the  process  of  distil- 
lation, condensation,  reboiling,  skimming,  etc.,  does  not 
always  make  unobjectionable  ice,  perfectly  clear,  without 
core  or  without  taste  and  flavor.  Ice  may  be  practically 
pure,  wholesome  and  palatable  while  containing  these 
defects,  and  although  most  successful  manufacturers 
know  how,  as  a  rule,  to  avoid  these  defects,  still,  occa- 
sionally they  turn  up  and  often  prove  to  be  a  great 
annoyance. 

WHITE  OR  MILKY  ICE. 

White  or  cloudy  or  milky  ice  is  generally  due  to  the 
presence  of  air  in  the  distilled  water;  it  is  caused  by 
deficient  reboiling  or  by  overworking  the  reboiler,  by  a 
deficient  supply  of  steam  to  the  distilled  water  condenser. 
In  the  latter  case,  a  vacuum  is  formed  through  the  rapid 
condensation  of  the  steam,  and  more  air  is  drawn  in 
and  mixed  with  the  steam  than  can  be  driven  away  by 
the  usual  extent  of  reboiling.  If  in  this  case  the  supply 
of  steam  cannot  be  increased,  the  amount  of  cooling 
water  running  over  the  condenser  must  be  reduced,  in 
order  to  keep  the  pressure  up  in  the  condenser.  Other- 
wise the  distilled  water  must  be  more  thoroughly 
reboiled.  Air  is  also  drawn  in  sometimes  during  the 
filling  of  the  cans,  through  leaks  in  the  distilled  water 
pipes,  etc. 

Frequently  milky  or  streaky  ice  is  also  due  to  leaks 
in  the  freezing  can,  through  which  brine  may  be  allowed 
to  mix  with  the  water  in  the  can,  which  will  then  show 
as  white  or  milky  ice  or  as  white  spots  or  streaks.  The 
salty  taste  of  these  parts  readily  shows  their  cause, 
which  may  be  remedied  by  mending  the  cans. 

ICE  WITH  WHITE  CORE. 

The  white  core  which  forms  in  the  ice  from  the  last 
portion  of  the  freezing  water  is  due  to  mineral  water 
(generally  carbonate  of  lime  and  magnesia)  derived  from 
the  natural  water,  from  which  it  has  not  been  success- 
fully separated,  this  separation  being  the  principal 
object  of  the  distilling  process.  In  most  cases  the  core 
is  caused  by  the  priming  of  the  boiler,  by  carrying  too 
much  water,  or  by  overworking  the  boiler  and  also  not 
blowing  off  the  boiler  often  enough,  in  which  case  the 
mineral  constituents  of  the  water  accumulate  and  in- 
crease the  danger  of  priming.  The  most  rational 


ICE  MAKING  AND  STORING.      ,  163 

remedy  in  this  case  is  boilers  large  enough  to  make 
overworking,  high  water  and  priming  entirely  impos- 
sible. Another  important  remedy  is  the  purification  of 
the  water  before  it  enters  the  boilers. 

ICE  WITH  RED  CORE. 

The  red  core  in  ice  is  brought  about  by  a  separation 
of  oxide  of  iron  in  the  ice,  which  was  kept  in  solution  in 
the  water  in  the  form  of  carbonate  of  iron.  This  sedi- 
ment is  nearly  always  derived  from  the  iron  of  the  plant, 
more  especially  the  coils.  It  frequently  sets  in  during 
the  second  season  of  the  working  of  a  plant,  and  then  is 
directly  traceable  to  the  rust  which  has  formed  within 
during  the  idle  months  or  during  shorter  stoppages. 
To  prevent  this,  the  pipes  and  tanks  might  be  kept 
filled  with  distilled  and  thoroughly  reboiled  water.  If 
the  water  supply  carries  much  carbonic  acid,  this  sub- 
stance may  contaminate  the  distilled  water  in  such  a 
manner  as  to  dissolve  iron  from  coils,  etc.,  which  is 
afterward  deposited  in  the  ice,  as  set  forth. 

It  has  also  been  proposed  to  use  pipe  tinned  inside 
for  the  distilled  water  condenser,  and,  if  possible,  tinned 
surface  throughout  the  distilled  water  plant,  to  avoid 
the  possibility  of  contamination  with  iron  from  this 
source.  If  the  water  supply  carries  carbonate  of  iron 
in  solution,  this  may  also  become  the  cause  of  a  red 
core,  but  only  in  case  the  boiler  primes  or  is  overworked 
and  foul,  and  if  the  filters  do  not  do  their  duty. 

The  formation  of  this  red  core  will  doubtless  be 
avoided  in  the  future  by  proper  treatment  of  the  water 
and  more  careful  management  of  boilers  and  plant. 
For  the  present,  in  cases  where  prevention  is  impossible, 
a  cure  may  be  effected  by  cooling  the  distilled  water 
down  to  about  36°  to  38°,  at  which  temperature  the  iron 
will  separate  and  may  be  separated  by  means  of  ordinary 
small  sand  or  sponge  filter. 

A  radical,  but  rather  expensive  and  troublesome, 
means  to  prevent  the  formation  of  a  core  of  any  kind, 
consists  in  the  removal  of  the  water  still  remaining  un- 
frozen in  the  nearly  complete  ice  block,  just  before  the 
core  begins  to  form,  by  means  of  a  syringe  and  refilling 
the  space  with  clear  distilled  water. 

DANGERS  OF  FILTRATION. 

A  core  in  the  ice  may  also  be  caused  by  mineral 
matter,  which  has  been  imparted  to  the  distilled  water 


164  MECHANICAL  REFRIGERATION. 

by  the  very  process  of  filtration.  When,  as  sometimes 
happens,  the  distilled  water  is  charged  with  carbonic 
acid  gas,  and  boneblack  (not  previously  chemically 
treated)  is  used  as  filtering  material,  the  water  will  take 
up  a  certain  amount  of  carbonate  of  lime  from  the  bone- 
black,  and  cause  a  white  core.  Other  impurities  in 
filtering  material  will  cause  similar  cores. 

COLOR,   TASTE  AND  FLAVOR  OF  ICE. 

Regarding  the  odor  and  taste  possessed  by  some  dis- 
tilled water,  or  by  ice  made  therefrom,  and  also  the 
greenish  color  shown  by  some  ice,  they  are  due  to  the 
presence  of  minute  quantities  of  volatile  matter  (be- 
longing to  the  hydrocarbon  class),  which  are  derived 
from  the  natural  water  supply  or  from  the  lubricating 
materials.  If  their  presence  is  due  to  the  water,  these 
defects,  as  in  fact  also  most  other  defects  in  ice,  will 
become  more  apparent  if  the  boilers  are  allowed  to  be- 
come foul ;  and,  on  the  other  hand,  if  the  boilers  are 
cleaned  and  blown  off  with  sufficient  frequency  (in  the 
case  of  vile  water  as  often  as  once  in  twenty-four  hours) 
these  defects,  like  others,  may  be  so  reduced  as  to  be- 
come almost  unnoticeable.  Priming  of  the  boilers,  of 
course,  also  increases  these  as  well  as  other  defects. 

If  odor,  taste  or  color  of  the  ice  are  derived  from  the 
lubricating  oil  (which  also  sometimes  causes  cloudy 
ice)  efficient  oil  'or  steam  filters,  kept  in  proper  order, 
are  the  best  remedy.  An  improper  and  excessive  use 
of  cylinder  oil  should  also  be  carefully  guarded  against. 

BEST  USE  OF  BONEBLACK. 

Where  these  preventive  remedies  do  not  apply,  the 
distilled  water  may  be  freed  from  these  defects  (taste 
and  odor)  by  filtering  it  through  granulated  boneblack  ; 
and  where  this  is  found  too  expensive,  as  in  the  absence 
of  means  for  revivifying  the  spent  boneblack,  the  latter 
may  be  used,  after  having  been  reduced  to  an  impalpa- 
ble powder.  In  this  shape  a  pound  or  two  of  boneblack 
will  go  a  long  way,  and  will  suffice  to  withdraw  any 
smell  or  taste  from  a  ton  of  water.  To  this  end  this  powder 
should  be  intimately  mixed  with  the  distilled  water  in 
the  said  proportion  before  the  last  filtration,  which  will 
retain  the  boneblack,  together  with  the  impurities  which 
it  has  absorbed  from  the  water. 

Blood  charcoal  will  act  even  more  efficiently  in  this 
respect,  but  it  is  very  doubtful  whether  its  superiority 


ICE  MAKING  AND  STOKING.  165 

to  boneblack,  powdered  equally  fine,  is  sufficient  to 
overcome  its  high  price  (eighty-five  cents  per  pound  for 
the  best  imported  article).  With  this  material  it  is  also 
important  to  make  sure  that  it  has  been  freed  from  all 
soluble  constituents  before  using. 

NUMBER    OF  FILTERS  REQUIRED. 

Regarding  the  number  and  kind  of  filters  required, 
it  would  appear  from  the  foregoing  that  this  question 
must  be  settled  separately  for  individual  cases.  When 
the  distilled  water  supply  is  charged  with  much  oily 
matter,  with  odoriferous  volatile  products,  and  also  with 
mineral  substances  held  in  solution,  we  shall  doubtless 
stand  in  need,  at  least  for  the  time  being,  of  an  oil  or 
steam  filter,  of  a  charcoal  or  boneblack  filter  (or  bone- 
black  powder)  and  of  a  filter  between  the  freezing  can 
and  the  distilled  water  or  cooling  tank. 

If  mineral  matters  were  entirely  absent  the  last  filter 
would  not  be  needed,  and  if  volatile  products  are  absent 
the  charcoal  or  boneblack  treatment  may  be  dispensed 
with,  and  vice  versa ;  and  in  case  where  the  vapor  from 
which  the  water  is  to  be  condensed  is  absolutely  pure, 
and  the  coils  and  tanks  of  the  condensing  apparatus 
likewise,  no  filters,  skimmerg  and  the  like  will  be  re- 
quired  at  all. 

It  is  to  be  hoped  that  within  the  near  future  the  nat- 
ural water  supplies  will  be  so  improved,  and  the 
management  of  boilers,  engines,  lubricators,  condensing 
coils,  reboilers,  etc.,  will  be  manipulated  universally  in 
such  a  manner  that  the  purity  of  the  ice  can  be  insured 
without  so  much  attention.  In  this  respect,  frequent 
cleaning  of  boilers,  blowing  out  of  coils  by  steam  when 
stopping  and  starting,  and  careful  lubricating  are  among 
the  first  points  to  be  considered. 

Under  all  circumstances,  however,  a  simple  but  effi- 
cient filter  between  distilled  water  storage  tank  and  the 
freezing  cans  will  always  be  found  a  valuable  help  and 
safeguard.  The  filtering  apparatus  recently  introduced 
for  this  purpose,  consisting  of  two  perforated  disks  with 
special  filtering  cloths  between,  is  a  neat  and  compact 
apparatus  which  seems  to  satisfy  all  demands  as  regards 
easy  application,  simple  operation,  economy  of  space, 
little  attention  and  efficiency. 

ROTTEN  ICE. 

When  complaints  are  made  about  the  "  quick  melt- 


166  MECHANICAL  REFRIGERATION. 

ing  away  "  of  manufactured  ice,  it  will  be  found  that  it 
is  generally  caused  by  incomplete  cakes,  or  cakes-  which 
have  not  completely  closed  in  the  center.  The  increased 
surface  thu8  given  to  a  cake  causes  it  to  melt  away 
quicker,  in  increasing  proportion  as  the  surface  of  the 
whole  increases  by  this  procedure.  For  these  reasons 
holes  in  ice  must  be  avoided,  and  every  piece  of  ice 
should  be  frozen  solid  all  over. 

So  called  rotten  ice  also  melts  away  quickly ;  it  is 
ice,  the  surface  of  which  is  also  increased  by  cracks  pro- 
ceeding from  the  outside  to  the  center.  Such  ice  is  fre- 
quently withdrawn  from  the  outside  layers  of  stored 
manufactured  ice  not  protected  by  mechanical  refrigera- 
tion during  the  storage,  and  the  application  of  such 
refrigeration  is  the  best  remedy  for  it. 

TEST  FOR  WATER  AND  ICE. 

Water  if  properly  distilled  (and  of  course  ice  made 
from  such  water,  likewise)  if  slowly  evaporated  on  a  piece 
of  platinum  foil  on  a  spirit  lamp  or  a  Bun^en  gas  burner, 
should  leave  no  solid  residue.  If  care  is  used  in  per- 
forming the  operation  a  piece  of  thin  glass  plate  may  be 
used  instead  of  the  platinum  foil. 

PURE  WATER. 

The  opinions  on  the  requirements  to  be  made  of  a 
water  supply  vary  considerably;  the  following  may  stand 
for  a  sample  of  what  some  authorities  demand  of  a  water 
fit  for  drinking  and  other  domestic  purposes,  and  in  some 
measure  it  may  also  be  applied  to  ice. 

1.  Such  water  should  be  clear,  temperature   not 
above  15°  C. 

2.  It  should  contain  some  air. 

3.  It  should  contain  in  1,000,000-parts  : 

Not  more  than  20  parts  of  organic  matter. 
Not  more  than  0.1  part  of  albuminoid  ammonia. 
Not  more  than  0.5  part  of  free  ammonia. 

4.  It  should  contain  no  nitrites,  no  sulphurated 
hydrogen,  and  only  traces  of  iron,  aluminum  and  mag- 
nesium.   Besides  the  mentioned   substances  it  should 
not  contain  anything  that  is  precipitable  by  sulphureted 
ammonia. 

5.  It  must  not  contract  any  odor  in  closed  vessels. 

6.  It  must  contain  no  saprophites  and  leptothrix 
and  no  bacteria  and  infusoria  in  notable  quantities. 


ICE  MAKING  AND  STORING  167 

*7.  Addition  of  sugar  must  cause  no  development  of 
fungoid  growth. 

8.  On  gelatine  it  must  not  generate  any  liquefying 
colonies  of  bacteria. 

DEVICES  FOR  MAKING  CLEAR  ICE. 

Besides  the  plate  system  and  the  use  of  distilled 
water,  a  number  of  contrivances  have  been  devised  for 
the  manufacture  of  clear  ice  from  natural  water.  The 
efficiency  of  these  devices  is  based  upon  the  motion  which 
they  keep  up  in  the  water  in  various  ways.  Their  de- 
tailed description  cannot  be  attempted  here;  moreover  it 
seems  that  they  have  net/  given  much  satisfaction  gener- 
ally; probably  they  are  too  cumbersome  and  too  uncer- 
tain in  their  performance. 

THE   CELL   SYSTEM. 

From  the  other  methods  in  use  for  ice  making,  we 
may  yet  mention  the  cell  system,  which  is  in  use  on  the 
continent  to  some  extent.  It  consists  of  a  series  of  walls 
of  cast  or  wrought  iron  placed  from  twelve  to  eighteen 
inches  apart,  the  space  between  each  pair  of  walls  being 
filled  with  the  water  to  be  frozen.  The  cooled  brine  cir- 
culates within  a  number  of  spaces  left  in  the  walls,  and 
the  ice  forms  on  the  walls,  increasing  in  thickness  until 
the  two  opposite  layers  meet.  If  thinner  blocks  are  re- 
quired, freezing  may  be  stopped  at  any  time,  and  the  ice 
removed.  In  order  to  detach  the  ice  from  the  walls 
warmer  brine  may  be  circulated  through  the  cell  walls  to 
loosen  the  ice.  It  stands  to  reason  that  impurities  of  the 
water  will  be  separated  from  the  same  on  the  ice,  if  the 
two  opposite  layers  are  not  allowed  to  meet.  It  will  take, 
however,  nearly  double  the  time  to  freeze  a  block  of  a 
given  thickness  if  the  two  layers  are  not  allowed  to  meet 
to  form  one  solid  block. 

COST  OF  REFRIGERATION. 

In  order  to  arrive  at  the  possible  remunerability  of 
a  refrigerating  plant  calculated  to  turn  out  artificial  ice, 
it  is  but  fair  to  compare  the  cost  of  the  latter  with  the 
price  of  pure  natural  ice  in  the  available  market.  If, 
however,  on  the  other  hand,  a  refrigerating  plant  is  cal- 
culated to  replace  natural  ice  in  the  cooling  of  storage 
room,  ice  boxes,  etc.,  the  above  calculation  must  be 
changed  as  a  matter  of  course, 


168  MECHANICAL  REFRIGERATION. 

CHAPTER  VI.— COLD  STORAGE. 

COLD  STORAGE. 

Cold  storage  in  general  comprises  the  preservation  of 
perishable  articles  by  means  of  low  temperature,  and  is 
one  of  the  principal  cases  to  which  artificial  refrigeration 
is  applied. 

STORAGE  ROOMS. 

Cold  storage  rooms,  like  ice  houses,  are  built  to  be  as 
perfectly  insulated  and  protected  as  possible  against  the 
egress  of  cold  and  ingress  of  heat.  They  are  kept  cold  by 
systems  of  pipe  lines  through  which  circulates  either  re- 
frigerated ammonia  (direct  expansion)  or  cooled  brine 
(brine  system).  The  size  of  the  house  depends  on  the  stor- 
age requirements;  they  should  be  built  as  nearly  square  as 
possible,  be  properly  ventilated,  have  double  doors  and 
windows,  and  all  other  protections  that  will  insure  the 
best  insulation  possible.  The  size  of  cold  storage  rooms 
varies  from  that  of  a  small  ice  box  of  a  few  cubic  feet 
capacity  to  that  of  gigantic  storehouses  of  several 
million  cubic  feet  space. 

CONSTRUCTION  OF  COLD  STORAGE  HOUSES. 

It  is  not  within  the  scope  of  this  treatise  to  go  into 
details  on  this  subject;  nevertheless  the  descriptions  of 
two  specimens  of  walls  for  insulated  buildings  for  storage 
and  other  purposes,  which  have  given  excellent  satis- 
faction, may  find  a  place  here. 

CONSTRUCTION  OF  WOOD. 

A  strong  and  well  insulated  wall  of  wood  may  be 
constructed  by  placing  2x  6-inch  studs  twenty-four  inches 
apart;  and  in  order  to  form  outside  of  wall  nail  on  them 
nrst  a  layer  of  1-inch  matched  boards,  then  a  layer  of  two- 
ply  paper,  and  again  a  layer  of  1-inch  matched  boards. 
On  the  inside  a  layer  of  1-inch  matched  boards  is 
nailed  on  the  studs,  and  against  these  boards  2x2-inch 
studs  are  placed  twenty-four  inches  apart.  In  order  to 
form  the  inside  of  wall  one  layer  of  1-inch  matched 
boards  is  nailed  on  the  2X 2-inch  studs,  then  a  layer  of 
two-ply  paper,  and  lastly  another  layer  of  1-inch  matched 
boards  on  top  of  this  paper.  The  spaces  left  between 
the  2x 2-inch  studs  are  left  as  air  spaces,  while  the  spaces 
between  the  2 X  6-inch  studs  are  filled  in  with  sawdust 
crushed  cork  or  the  like. 


COLD  STORAGE.  169 

CONSTRUCTION  OF  BRICK  AND  TILES. 

For  brick  and  tile  construction  the  outside  of  the 
walls  is  formed  of  a  brick  wall  sixteen  inches  or  more  in 
thickness,  according  to  size  and  height  of  building.  On 
the  inside  the  wall  is  plastered.  Again,  a  wall  built  of 
4-inch  hollow  tiles  is  placed  at  a  distance  of  three  inches 
from  the  plaster  coating  of  the  brick  wall,  and  a  coat  of 
plaster  or  cement  on  tiles  on  the  inside  finishes  the  whole 
wall.  The  space  between  the  tiles  and  brick  wall  may 
bo  filled  in  with  cork,  sawdust  or  some  other  insulating 
material. 

If  the  space  between  tiles  and  brick  is  filled  with 
mineral  wool,  the  wall  represents  a  fire-proof  structure. 

OTHER  CONSTRUCTIONS. 

The  following  materials  and  dimensions  have  been 
iccommended  for  walls  of  cold  chambers  by  Taylor: 

Fourteen-inch  brick  wall,  3%-inch  air  space,  9-inch 
brick  wall,  1-inch  layer  of  cement,  1-inch  layer  of  pitch, 
2x3-inch  studding,  layer  of  tar  paper,  1-inch  tongued  and 
grooved  boarding,  2 X 4-inch  studding,  1-inch  tongued 
and  grooved  board,  layer  of  tar  paper,  and,  finally,  1- 
inch  tongued  and  grooved  boarding,  the  total  thickness 
of  these  layers  or  skins  being  3  feet  3  inches. 

Thirty- six-inch  brick  wall,  1-inch  layer  of  pitch,l-inch 
sheathing,  4-inch  air  space,  2 X  4-inch  studding,  1-inch 
sheathing,  3  inch  layer  of  mineral  or  slag  wool,  2x4-inch 
studding,  and,  finally,  1-inch  sheathing;  total  thickness  4 
feet  7  inches. 

Fourteen-inch  brick  wall,  4-inch  pitch  and  ashes,  4- 
inch  brick  wall,  4-inch  air  space,  14-inch  brick  wall;  total 
thickness  3  feet  4  inches. 

Fourteen-inch  brick  wall,  6-inch  air  space,  double 
thickness  of  1-inch  tongued  and  grooved  boards,  with  a 
layer  of  water-proof  paper  between  them,  2-inch  layer  of 
best^quality  of  hair  felt,  second  double  thickness  of  1- 
inch  tongued  and  grooved  boards,  with  a  similar  layer  of 
paper  between  them;  total  thickness,  2  feet  2  inches. 

Fourteen-inch  brick  wall,  8-inch  layer  of  sawdust, 
double  thickness  of  1-inch  tongued  and  grooved  boards, 
with  a  layer  of  tarred  water-proof  paper  between  them, 
2-inch  layer  of  hair  felt,  second  double  thickness  of  1- 
inch  tongued  and  grooved  boards  with  similar  layer  of 
paper  between  them;  total  thickness,  2  feet  4>£  inches. 


170  MECHANICAL  REFRIGERATION. 

The  cold  storage  chambers  built  at  the  St.  Kather- 
ine  dock,  London,  are  constructed  as  follows: 

On  the  concrete  floor  of  the  vault,  as  it  stood  origi- 
nally, a  covering  of  rough  boards  l1^  inches  in  thickness 
was  laid  longitudinally.  On  this  layer  of  boards  were 
then  placed  transversely,  bearers  formed  of  joist  4% 
inches  in  depth  by  3  inches  in  width,  and  spaced  21  inches 
apart.  These  bearers  supported  the  floor  of  the  storage 
chamber,  which  consisted  of  2%-inch  battens  tongued 
and  grooved.  The  4^-inch  wide  space  or  clearance 
between  this  floor  and  the  layer  or  covering  of  rough 
boards  upon  the  lower  concrete  floor  was  filled  with 
well  dried  wood  charcoal.  The  walls  and  roof  were 
formed  of  uprights  5^x3  inches  fixed  upon  the  floor 
joists  or  bearers,  and  having  an  outer  and  inner  skin 
attached  thereto;  the  former  consisting  of  2-inch  boards, 
and  the  latter  of  two  thicknesses  or  layers  of  13^-inch 
boards  with  an  intermediate  layer  of  especially  prepared 
brown  paper.  The  5^-inch  clearance  or  space  between 
the  said  inner  and  outer  skeins  of  the  walls  and  roof 
was  likewise  filled  with  wood  charcoal,  carefully  dried. 

CONSTRUCTION  OF  SMALL  ROOMS. 

Small  storage  rooms,  down  to  ice  boxes,  are  always 
built  of  wood,  paper,  cork,  etc.,  on  lines  similar  to  those 
given  for  wooden  walls,  but  with  endless  variations. 

COKSTBUCTIONS  AND  THEIR  HEAT  LEAKAGE. 

The  following  construction  of  walls  for  cold  storage 
buildings,  taken  from  the  catalogue  of  the  Fred  W. 
Wolf  Co.,  have  also  been  practically  tested,  and  the  ap- 
proximate heat  leakage  through  them  per  square  foot 
and  per  degree  of  difference  in  temperature  between  in- 
side and  outside  of  the  room,  is  also  given  in  British 
thermal  units  in  twenty-four  hours. 

FIREPROOF  WALL  AND  CEILING. 

Brick  wall  of  thickness  to  suit  height  of  building, 
3-inch  scratched  hollow  tiles  against  brick  wall,  4-inch 
space  filled  with  mineral  wool,  3-inch-  scratched  hollow 
tiles,  cement  plaster.  Heat  leakage  0.70  B.  T.  U. 

The  ceiling  to  match  this  wall  consists  of  the  follow- 
ing layers  :  Concrete  floor,  3-inch  book  tiles,  6-inch  dry 
underfilling,  double  space  hollow  tile  arches,  cemeni 
plaster.  Heat  leakage  0.80  B,  T.  U. 


COLD  STORAGE.  171 

WOOD  INSULATION  AGAINST  BRICK  WALL. 

The  following  wood  insulation  against  a  brick  wall 
has  a  leakage  of  1.74  B.  T.  U.,  and  consists  of  the  fol- 
lowing layers : 

Brick  wall,  against  which  are  nailed  wooden  strips 
1X2  inches.  On  these  are  nailed  two  layers  of  1-inch 
sheathing  with  two  layers  of  paper  ibetween  ;  next  we 
have  2  x  4-inch  studs  sixteen  inches  apart,  filled  in  be- 
tween with  mineral  wool,  1-inch  matched  sheathing,  two 
Ifyers  of  paper;  1  X  2-inch  strips,  sixteen  inches 
apart  from  centers ;  double  1-inch  flooring  with  two 
layers  of  paper  between. 

CONSTRUCTIONS  OF  WOOD. 

The  following  constructions  of  wall,  ceiling  and 
floor  may  be  followed  for  cold  storage  rooms  when  built 
of  wood : 

The  wall  is  constructed  as  follows :  Outside  siding, 
two  layers  of  paper,  1-inch  matched  sheathing,  2x6- 
inch  studs,  sixteen  inches  apart  from  centers,  two  layers 
of  1-inch  sheathing,  with  two  layers  of  paper  between, 
2  X  4-inch  studs,  sixteen  inches  apart  from  centers,  filled 
M  between  with  mineral  wool,  1-inch  sheathing,  two 
layers  of  paper,  2  x  2-inch  strips,  sixteen  inches  from 
center  to  center,  two  layers  1-inch  flooring,  with  two 
layers  of  paper  between.  The  heat  leakage  through 
this  wall  is  2.90  B.  T.  U. 

The  ceiling  has  the  following  details : 

A  double  1-inch  floor  with  two  layers~of  paper  be- 
tween, 2  x  2-inch  strips,  sixteen  inches  apart  from  cen- 
ter, filled  in  between  with  mineral  wool,  two  layers  of 
paper,  1-inch  matched  sheathing,  2  X  2-inch  strips, 
sixteen  inches  apart,  filled  between  with  mineral  wool, 
two  layers  of  paper,  1  inch  matched  sheathing,  joists, 
double  1-inch  flooring,  with  two  layers  of  paper  between.. 
The  heat  leakage  through  this  ceiling  amounts  to  2.17 
B.  T.  U. 

The  details  of  the  floor  are  as  follows : 

Two-inch  matched  flooring,  two  layers  of  paper, 
1-inch  matched  sheathing,  4  X  4-inch  sleepers,  sixteen 
inches  apart  from  centers,  filled  between  with  mineral 
wool,  double  1-inch  matched  sheathing,  with  twelve  lay- 
ers of  paper  between,  4  x  4-inch  sleepers  sixteen  inches 
aprxt  from  centers  imbedded  in  12-inch  dry  under- 
filling. 


172  MECHANICAL  REFRIGERATION. 

The  heat  leakage  through  this  floor  is  given  at  1.92 
B.  T.  U. 

PIPING. 

All  ammonia  brine  and  heating  pipes,  headers  and 
mains  ought  to  be  in  the  corridors,  well  insulated. 

CONSTRUCTIONS  WITH  AIR  INSULATIONS. 

In  the  following  constructions,  taken  from  the  cata- 
logue of.  the  De  La  Yergne  Refrigerating  Machine  Co., 
the  insulating  spaces  are  made  by  confined  bodies  of  air, 
it  being  claimed  by  some  that  any  filling  of  these  spaces 
with  loose  non-conducting  material  will  settle  in  places. 
The  penetration  of  air  and  moisture  is  specially  guarded 
against  by  the  use  of  pitch  in  connection  with  brick  or 
stone,  or  by  paper  where  wood  is  used.  Joints  between 
boards  should  be  laid  in  white  lead  and  corners  should 
be  protected  by  triangular  pieces  of  wood  with  paper 
placed  carefully  behind. 

CONSTRUCTIONS  OF  WOOD. 

The  main  walls  of  buildings  (for  refrigerators  of 
hotels,  restaurants  and  cold  storage  in  general)  built  on 
the  foregoing  principles,  have  the  following  details, 
commencing  inside:  ,% -inch,  spruce,  insulating  paper, 
%-inch  spruce,  1-inch  air  space,  twelve  inches  square, 
%-inch  spruce,  insulating  paper,  %-inch  spruce,  1-inch 
air  space,  ,%-inch  spruce,  insulating  paper,  %-inch  hard 
wood. 

The  ceiling  or  floor,  when  the  room  above  or  below 
is  not  cooled,  has  the  following  details,  commencing  be- 
low the  joists  :  ,%-inch  board,  insulating  paper,  %-inch 
board,  floor  beams,  ^-inch  board,  insulating  paper, 
,%-inch  board  (two  inches  air  space,  %-inch  board,  insul- 
ating paper,  %  inch  board).  If  room  above  is  cooled,  the 
parts  in  parenthesis  may  be  omitted. 

Partitions  between  two  cooled  rooms,  where  differ- 
ence of  temperature  does  not  exceed  20°,  may  be 
constructed  as  follows  :  ,%-inch  board,  insulating  paper, 
^-inch  board,  1^-inch  air  space,  ,%-inch  board,  insu- 
lating paper,  %-inch  board. 

For  main  inside  walls  between  two  rooms,  of  which 
one  is  not  cooled,  the  following  construction  may  be 
followed  :  %-ineh  board,  insulating  paper,  %-inch  board, 
two  inches  air  space,  %-inch  board,  insulating  paper, 
^6-inch  board,  two  inches  air  space,  ,%-inch  board,  in- 
sulating paper,  Ji-mch  board. 


C6LD  STORAGE.  173 

CONSTRUCTION  IN  BRICK. 

The  outer  walls  in  buildings  of  brick  may  be  con- 
structed as  follows,  commencing  outside  :  Brick  wall  of 
proper  strength,  two  coats  of  pitch,  two  inches  air  space, 
%-inch  board,  insulating  paper,  Jg-inch  board,  two 
inches  air  space,  ^-inch  board,  insulating  paper, 
%-inch  board. 

The  ceiling  may  be  constructed  as  follows,  when 
room  above  is  not  cooled  (commencing  at  the  top  layer): 
One  inch  asphalt,  two  inches  concrete,  brick,  wooden 
stiips,  ,%-inch  board,  insulating  paper,  ^-inch  board, 
two  inches  air  space,  %-inch  board,  insulating  paper, 
^-inch  board. 

If  the  difference  in  temperature  between  the  lower 
and  upper  room  does  not  exceed  20°  F.  the  following 
construction  for  ceiling  may|be  used :  One  inch  asphalt, 
two  inches  concrete,  brick. 

SURFACE  OF  INTERIOR  WALLS. 

It  is  claimed  that  the  porosity  of  the  surfaces  of 
walls  in  cold  storage  rooms  is  in  a  measure  responsible 
for  the  spoiling  of  provisions.  Such  walls,  if  made  of 
cement,  plaster  and  similar  semi-porous  material,  pos- 
sess sufficient  moisture  to  give  rise  to  all  sorts  of 
putrefactive  and  bacterial  growths,  allowing  them  to 
thrive  under  favorable  conditions.  A  further  objection 
to  this  kind  of  walls  is  the  quicker  radiation  of  heat 
through  them.  For  these  reasons  it  has  been  urged 
that  the  walls  in  cold  storage  houses  for  cold  and  espe- 
cially meat  storage,  should  be  made  from  porcelain,  and 
that  they  should  be  cleaned  several  times  during  the 
year. 

REFRIGERATION  REQUIRED. 

The  amount  of  refrigeration  required  in  a  given  case 
depends  on  a  number  of  circumstances  and  conditions, 
the  size  of  the  room,  the  frequency  with  which  the  arti- 
cles are  brought  in  and  removed,  their  temperature,  spe- 
cific heat  of  produce,  etc.  For  these  reasons  it  is  impos- 
sible to  give  a  simple  general  rule,  and  the  following 
figures,  which  are  frequently  used  in  rough  calculations, 
must  be  considered  as  approximations  only: 

For  storage  rooms  of  1,000,000  cubic  feet  and  over,  20 
to  40  B.  T.  U.  per  cubic  foot  per  twenty- four  hours. 

For  storage  rooms  50,000  cubic  feet  and  over,  40  to  70 
B.  T.  U.  per  cubic  foot  per  twenty-four  hours. 


174  MECHANICAL  KEFRlGEKAflOK. 

For  boxes  or  rooms  1,000  cubic  feet  and  over,  50  to  100 
B.  T.  U.  per  cubic  foot  per  twenty-four  hours. 

For  boxes  less  than  100  cubic  feet,  100  to  300  B.  T.  U. 
per  twenty-four  hours. 

For  rooms  in  which  provisions  are  to  be  chilled, 
about  50  percent  additional  refrigeration  may  be  allowed 
in  approximate  estimations.  For  actual  freezing  the 
amount  should  be  doubled  (see  also  Meat  Storage). 

PIPING  AND  REFRIGERATION. 

The  foregoing  rules  on  refrigerating  capacity,  aa 
well  as  those  given  elsewhere,  and  including  also  the 
rules  for  piping  given  on  pages  134  to  138,  and  elsewhere, 
have  in  common  one  vital  defect,  in  that  they  fit  only 
one  given  temperature  or  rooms  of  one  certain  size. 
This  condition  of  things  necessarily  gives  rise  to  numer- 
ous misunderstandings  and  many  errors,  and  for  this 
reason  I  have  endeavored  to  outline  some  tables  which 
would  do  equal  justice  to  all  the  elements  involved,  or 
at  least  indicate  how  this  could  be  done.  The  desire  of 
the  author  to  supply  such  much  needed  tables  without 
further  delay  must  be  an  excuse  for  their  imperfections,as 
so  far  only  comparatively  few  of  the  values  given  therein 
could  be  verified  by  data  taken  from  actual  experience. 

TABULATED  REFRIGERATING  CAPACITY. 

The  amount  of  refrigeration  required  for  cold  storage 
buildings  for  provisions,  beer,  meat,  ice,  etc.,  depends,  as 
has  been  mentioned  repeatedly,  principally  on  the  size  of 
the  rooms,  their  insulation,  the  maximal  outside  tempera- 
ture and  the  minimal  inside  temperature  (leaving  open- 
ings, opening  of  doors  and  refrigeration  of  contents, 
etc.,  out  of  the  question).  The  chief  variants  among 
these  quantities  are  the  degree  of  insulation,  the  size 
of  rooms  or  houses  and  the  minimal  temperature  within 
(the  latter  depending  on  the  objects  of  storage) ;  while 
for  the  maximal  outside  temperature  we  may  agree 
upon  a  certain  fixed  quantity,  which  for  approximate 
calculations  will  apply  for  a  large  territory  of  the  United 
States,  at  least. 

We  may  safely  take  this  maximal  temperature  for 
most  of  the  United  States  at  80°  to  90°  F.,  so  it  will  amply 
cover  8£°  F. 

Doing  this,  we  can  readily  outline  a  table  which  will 
show  the  amount  of  refrigeration  required  for  rooms  of 
different  sizes  and  of  different  insulation  for  any  given 


COLD  STORAGE. 


175 


temperature,  as,  for  instance,  the  following  table,  which 
gives  the  number  of  cubic  feet  in  cold  storage  buildings 
which  can  be  covered  by  one  ton  of  refrigerating  capac- 
ity for  rooms  of  different  sizes,  for  different  temperatureg 
and  for  different  (excellent  and  poor)  insulation  during  a 
period  of  twenty-four  hours : 

NUMBER   OF    CUBIC    FEET    COVERED    BY   ONE   TON    REFRIG- 
ERATING CAPACITY   FOR   TWENTY- FOUR  HOURS. 


Size  of 
building- 

Temperature  °  F. 

in  cub.  ft. 

Insulation. 

more  or 

less. 

0° 

10° 

20° 

30° 

40° 

50° 

excellent 

150 

600 

800 

1,000 

1,600 

3,000 

100 

poor 

70 

300 

400 

600 

900 

2,000 

1   OOO 

excellent 

500 

2,500 

3,000 

4,000 

6,000 

12,000 

poor 

250 

1,500 

1,800 

2,500 

5,000 

10,000 

10,000 

excellent 
poor 

700 
300 

3,000 
1,800 

4,000 
2,500 

6,000 
3,500 

9,000 
7,000 

18,000 
14,000 

30,000 

excellent 
poor 

1,000 
500 

5,000 
3,000 

6,000 
3,500 

8,000 
5,000 

13,000 
11,000 

25,000 
20,000 

100,000 

excellent 
poor 

1,500 
800 

7,500 
4,500 

9,000 
5,000 

14,000 
8,000 

20,000 
16,000 

40,000 
35,000 

The  next  table  is  constructed  on  the  same  basis, 
giving  the  amount  of  refrigeration  required  per  cubic 
foot  of  space  for  storage  rooms  of  different  sizes  for  dif- 
ferent temperatures,  expressed  in  British  thermal  units, 
and  for  a  period  .of  twenty-four  hours. 

REFRIGERATING     CAPACITY     IN    B.     T.     U.     REQUIRED     PER 
CUBIC  FOOT  OF   STORAGE  ROOM   IN  TWENTY-FOUR  HOURS. 


Size  of 

building1 

Temperature  °  P. 

in  cub.  ft. 

Insulation. 

more  or 

less. 

0° 

10° 

20" 

30° 

40° 

50° 

10O 

excellent 

1,800 

480 

360 

284 

180 

95 

AVW 

poor 

4,000 

960 

480 

470 

330 

140 

1  000 

excellent 

550 

110 

95 

70 

47 

24 

J.,  \J\J\J 

poor 

1,100 

190 

165 

110 

55 

28 

10,000 

excellent 
poor 

400 
900 

95 
160 

70 
110 

47 
81 

30 
40 

16 

20 

30,000 

excellent 

280 

55 

47 

35 

22 

11 

poor 

550 

95 

81 

55 

26 

14 

100,000 

excellent 
poor 

190 
350 

38 
63 

30 

55 

20 
35 

14 
18 

7 
4 

176 


MECHANICAL  REFRIGERATION. 


The  expression  "  excellent  insulation"  in  the  above 
and  following  tables  may  be  taken  to  refer  to  wallu, 
ceilings,  etc.,  the  heat  leakage  of  which  does  not  exceed 
two  B.  T.  U.  for  each  degree  F.  difference  in  tempera- 
ture per  square  foot  in  twenty-four  hours ;  and  the  ex- 
pression "poor  insulation"  may  be  taken  to  refer 
to  walls,  etc.,  the  heat  leakage  in  which  amountn 
to  four  B.  T.  U.  and  more.  The  average  of  the  amounts 
of  refrigeration,  space  and  pipes  given  in  the  tables  may 
be  taken  for  average  good  insulation,  other  circum- 
stances being  equal. 

TABULATED  AMOUNTS  OF  PIPING. 

The  amount  of  piping  required  for  cold  storage 
buildings  depends,  in  the  first  place,  on  the  amount  of  re- 
frigeration to  be  distributed  thereby,  and  therefore 
indirectly  on  the  same  conditions  as  does  the  amount  of 
refrigeration  required.  In  addition  thereto  the  amount 
of  piping  also  depends  on  the  difference  between  the 
temperature  within  the  refrigerating  or  direct  expan- 
sion pipes,  and  without.  As  this  difference  may  be 
varied  arbitrarily  by  the  operator,  and  necessarily  differi 
for  different  storage  temperatures,  it  would  be  veiy 
difficult  to  arrange  a  table  fitting  all  possible  conditions. 

However,  it  stands  to  reason  that  for  each  storage 
temperature  there  is  one  preferable  brine  or  expansion 
temperature,  and  the  accompanying  tables  on  piping  are 
expected  to  fit  these  temperatures  for  practical  calcula- 
tions. 

LINEAL   FEET   OF   1-INCH   PIPE  REQUIRED   PER    CUBIC 
FOOT   OF    COLD  STORAGE  SPACE. 


Size  of 

building 

Temperature  °  F. 

in  cub.  ft. 

Insulation. 

more  or 

less. 

0° 

10° 

20° 

30° 

40° 

50° 

100 

excellent 

3.0 

0.78 

0.48 

0.36 

0.24 

0.15 

JL\J\J 

poor 

6.0 

1.50 

0.90 

0.66 

0.48 

0.30 

1,000 

excellent 

1.0 

0.26 

0.16 

0.12 

0.08 

0.05 

poor 

2.0 

0.50 

0.30 

0.22 

0.16 

0.10 

10,000 

excellent 

0.61 

0.16 

0.10 

0.075 

0.055 

0.035 

poor 

1.2 

0.33 

0.20 

1.15 

0.11 

0.07 

30  000 

excellent 

0.5 

0.13 

0.08 

0.06 

0.040 

0.025 

poor 

1. 

0.25 

0.15 

0.11 

0.03 

0.05 

100,000 

excellent 

0.38 

0.10 

0.06 

0.045 

0.03 

0.009 

poor 

0.75 

0.20 

0.12 

0.09 

0.06 

0.018 

COLD  STORAGE. 


177 


The  quantities  of  pipe  given  in  the  foregoing  table 
refer  to  direct  expansion,  and  should  be  made  one  and 
one-half  times  to  twice  that  long  for  brine  circulation. 
They  also  refer  to  1-inch  pipe,  and  by  dividing  the 
lengths  given  by  1.25,  or  multiplying  them  by  0.8,  the 
corresponding  amount  of  1^-inch  pipe  is  found.  To 
find  the  corresponding  amount  of  2-inch  pipe,  the  length 
given  in  the  table  must  be  divided  by  1.08,  or  multiplied 
by  0.55. 

The  next  table  is  for  the  same  purpose  as  the  one 
preceding,  but  it  shows  the  number  of  cubic  feet  of  storage 
building  which  will  be  covered  by  one  foot  of  1-inch  pipe 
during  a  period  of  twenty-four  hours  for  different  sized 
rooms  and  different  storage  temperatures. 

NUMBER     OF      CUBIC     FEET      COVERED     BY     ONE     FOOT    OF 
ONE-INCH    IRON    PIPE. 


Size  of 

building- 

Temperature  °  F. 

in  cub.  ft. 

Insulation. 

more  or 

less. 

0° 

10° 

20° 

30° 

40° 

50° 

100 

excellent 

0.3 

1.3 

2.1 

2.8 

4.2 

7.0 

A.\J\J 

poor 

0.15 

0.7 

1.1 

1.5 

2.1 

3.5 

1  000 

excellent 

1.0 

4. 

6.0 

8.4 

12.4 

20. 

.L,  \J\J\J 

poor 

0.5 

2. 

3.2 

4.5 

6.2 

1.0. 

10,000 

excellent 
poor 

1.7 

0.85 

6. 
3. 

10. 

5. 

13. 
6.5 

18. 
9. 

28. 
14. 

30,000 

excellent 

2.0 

8. 

14. 

18. 

25. 

40. 

poor 

1.0 

4. 

7. 

9. 

13. 

20. 

100,000 

excellent 
poor 

2.6 
1.3 

10. 

5. 

17. 
8.5 

22. 
11. 

33. 
17. 

110. 
55. 

The  number  of  cubic  feet  of  space  given  in  the  last 
table  as  being  covered  by  one  lineal  foot  of  pipe  refers 
to  direct  expansion,  and  only  one-half  to  two-thirds  of 
that  space  would  be  covered  by  the  same  amount  of 
pipe  in.  case  of  brine  circulation. 

The  figures  in  this  table  also  refer  to  1-inch  pipe ; 
and  to  find  the  corresponding  amounts  of  cubic  feet  of 
space  which  would  be  covered  by  one  lineal  foot  of  1^- 
inch  pipe,  the  numbers  given  in  the  table  have  to  be 
multiplied  by  1.25  or  be  divided  by  0.8.  To  find  the 
corresponding  amount  of  space  which  will  be  covered  by 
one  lineal  foot  of  2-inch  pipe,  the  numbers  given  in  the, 
table  must  be  multiplied  by  1.8  or  divided  by  0.55, 


178  MECHANICAL  REFRIGERATION. 

The  foregoing  tables  are  calculated  for  a  maximum 
outside  temperature  of  80°  to  90°  F.  If  the  same  is  ma- 
terially more  or  less  about  10  per  cent  of  refrigeration 
and  piping  should  be  added  or  deducted  for  every  5°  F. 
more  or  less,  as  the  case  may  be. 

TABLES  FOR  REFRIGERATING  CAPACITY. 

The  accompanying  table  designed  by  Criswell  is  cal- 
culated on  the  lines  laid  out  in  the  foregoing  paragraphs, 
on  the  assumption  that  the  walls,  ceiling  and  floor  ol 
the  cold  storage  building  have  an  average  heat  leak- 
age of  three  B.  T.  U.  per  square  foot  in  each  twenty-four 
hours  for  each  degree  Fahrenheit  difference  in  tempera4 
ture  outside  and  inside  of  building.  The  maximum 
temperature  is  taken  at  82°  F.  Accordingly  the  total 
refrigeration  for  such  .a  building  is  found  by  multiplying 
its  total  surface  in  square  feet  (.third  column  of  table) 
by  3,  and  the  difference  between  the  temperature  in  de- 
grees Fahrenheit  within  the  storage  building  and  82°  F. 
It  is  then  divided  by  284,000  to  reduce  the  refrigerating 
capacity  to  tons  of  refrigeration. 

We  will  take  for  an  example  the  building,  25x40x10. 
Its  surface  is  3,300  square  feet,  and  the  total  refrigera- 
tion required  for  a  temperature  of  32°  within  the  cold 

495  000 
storage  house  is  therefore  3,300x3x(82-32)=2g^-Q^ 

1.53  tons,  or,  in  round  numbers,  1.5  tons. 

The  building  here  referred  to  contains  10,000  feet, 

i  n  nno 

consequently  one  ton  of  refrigeration  would  cover      * 

1.51 

=6,600  cubic  feet  of  such  a  building.  Tnis  figure  should 
agree  with  the  corresponding  figure,  given  in  the  accom- 
panying table  (at  least,  approximately  so),  some  of  the 
figures  in  the  table  being  obtained  by  interpolation  or 
averaging.  If  we  compare  this  table  with  the  table 
given  on  page  175  we  will  note  several  apparent  discrep- 
ancies. They  are  explained  by  the  desire  to  give  a  very 
liberal  estimate  in  the  tables  on  page  175,  and  to  make 
allowance  not  only  for  the  refrigerating  of  the  contents, 
but  also  for  the  opening  of  doors.  These  are  doubtless 
the  reasons  why  the  refrigerating  capacity  for  smaller 
rooms  in  table  on  page  175  appears  so  large,  especially  at 
lower  temperatures,  as  in  these  cases  the  opening  of 
cjoors,  etc.,  acts  most  wastefully. 


COLD  STORAGE.  179 

TABLE  FOR  REFRIGERATING  CAPACITY. 


x  x 
Sl§§ 


gggggggggggM 


S 


•1 


Contents, 
iubic  feet. 


Surface 

in  square 

feet. 


Ratio 
cubic  feet 
to  square 

feet. 


?2 


5  fc  C  S  o>  0= 


° 


JlfggflHf 


s 


ii 

§3 


DOORS  IN  COLD  STORAGE. 

\t  may  not  be  amiss  on  this  occasion  to  state  that  the 
doors  of  cold  storage  buildings  and  rooms  and  ice  boxes 
play  a  most  important  r6le  in  the  economy  of  a  plant; 
and  therefore  their  construction,  which  is  frequently 
left  to  the  discretion  of  an  ordinary  carpenter,  is  a  mat- 
ter of  the  greatest  importance.  Not  only  should  they  be 
constructed  on  the  basis  of  the  least  heat  transmission, 
but  so  framed  and  hung  as  to  be  tight  and  remain  so  for 
the  longest  possible  time,  as  well  as  open  freely  at  all 
times.  Readjustments  long  neglected  involve  financial 


180  MECHANICAL  REFRIGERATION. 

losses  in  many  directions,  often  expensive  repairs,  when 
a  proper  construction  would  avoid  both  by  rendering  the 
first  needless.  Facility  for  easily  and  quickly  opening 
and  closing,  fastening  and  unfastening  is  most  import- 
ant. Workmen  persistently  leave  doors  open  while  going 
in  and  out  if  these  points  be  neglected,  with  a  consequent 
great  ingress  of  heat  and  moisture.  For  this  reason  it  is 
but  fair  to  recognize  the  laudable  exertion  of  those  firms 
who  make  the  rational  construction  of  doors  used  in  cold 
storage  buildings,  rooms,  etc.,  a  special  feature. 

CALCULATED  REFRIGERATION. 

For  more  exact  estimates  the  refrigeration  required 
in  a  given  case  may  be  calculated  by  allowing  first  for 
the  refrigeration  required  to  keep  the  storage  at  a  cer- 
tain given  temperature  in  consequence  of  the  radiation 
through  walls;  and  second  for  the  refrigeration  re- 
quired to  cool  the  articles  or  provisions  from  the  tem- 
perature at  which  they  enter  the  storage  room  down  to 
the  temperature  of  the  latter. 

RADIATION  THROUGH  WALLS. 

If  the  number  of  square  feet  contained  in  a  wall, 
ceiling,  floor  or  window  be  /,  the  number  of  units  of  re- 
frigeration, jR,  that  must  be  supplied  in  twenty-four  hours 
to  offset  the  radiation  of  such  wall,  ceiling  or  floor,  may 
be  found  after  the  formula: 

B=fn(t  —  tl)'B.  T.  units, 
or  expressed  in  tons  of  refrigeration 


In  these  formulae  t  and  tt  are  the  temperatures  on  each 
side  of  the  wall,  and  n  the  number  of  B.  T.  units  of  heat 
transmitted  per  square  foot  of  such  surface  for  a  differ- 
ence of  1°  F.  between  temperature  on  each  side  of  wall 
in  twenty-four  hours.    The  factor  n  varies  with  the  con- 
struction of  the  wall,  ceiling  or  flooring,  from  1  to  5. 

For  single  windows  the  factor  n  may  be  taken  at  12, 
and  for  double  windows  at  7  (  Box). 

For  different  materials  one  foot  thick  we  find  the 
following  values  for  n: 
For  pine  wood  .......  2.0  B.  T.  U.       For  sawdust  .........  1.1  B.  T.  U. 

"   mineral  wool  ...  1.6  "  -  "   charcoal,  pow'd  1.3  " 

"   granulated  cork  1.3  "  "   cotton  ..........  0.7  " 

"  Tyood  ashes  .....    l.Q  "    "    *  "  soft  paper  felt  .  P-§  "    "   " 


COLD   STORAGE. 


181 


For  brick  walls  of  different  thicknesses  the  factor  n 
may  be  taken  as  follows  after  Box  : 
l/2  brick 


1 

i* 

3 
4 


4*4  inches  thick  n  =  5.5  B.  T.  Units. 
=  4.5 

14    •  "      '    =  3.6 

18  "      '    =  3.0 


=  2.6 


For  walls  of  masonry  of  different  thicknesses  the 
factor  n  may  be  taken  as  follows  after  Box: 


Stn 

ne  walls 

B 

inches  thick,  n  = 

8.2 

B. 

T. 

u. 

" 

18 
24 

80 

aa 

M 

;;  - 

r>.o 

4.5 
4.:} 
4.1 

= 

: 

\ 

German  authorities  give  values  for  n  which  are  less 
than  one-half  of  the  values  here  quoted. 

For  air  tight  double  floors  of  wood  properly  filled  un- 
derneath so  that  the  atmosphere  is  excluded,  and  for 
ceilings  of  like  construction,  n  is  equal  to  about  2  B.  T. 
U.  An  air  space  sealed  off  hermetically  between  two 
walls  has  the  average  temperature  of  the  outside  and  in- 
side air,  hence  its  great  additional  insulating  capacity. 
If  the  air  space  is  hermetically  sealed  inside  and  outside, 
it  appears  that  its  thickness  is  immaterial;  half  an  inch 
is  as  good  as  three  inches. 

If  a  wall  is  constructed  of  different  materials  having 
different  known  values  for  n,  viz.,  wlt  n2,  ^3,  etc.,  and 
the  respective  thicknesses  in  feet  d^d2,  d3,  the  value,  n, 
for  such  a  compound  wall  may  be  found  after  the  form- 
ula of  Wolpert,  viz.  : 


In  case  of  an  air  space  perfectly  sealed  off  the  factor 
n  may  be  determined  for  that  portion  of  the  wall  between 
the  air  space  and  the  outside,  which  value  is  then  in- 
serted into  the  formula— 


But  in  this  case  while  1  1  stands  for  the  maximum  out- 
side temperature  t  stands  for  the  temperature  of  the  air 
space,  which  may  be  averaged  from  the  inside  and  outside 
temperature,  taking  into  consideration  the  conductibility 
and  thickness  of  the  component  parts  of  the  wall. 

In  the  selection  of  insulating  substances,  their  power 
to  withstand  moisture  plays  an  important  part  in  most 
cases.  In  this  respect  cork  is  a  very  desirable  material, 


182 


MECHANICAL  REFRIGERATION. 


likewise  pitch  and  mixtures  of  asphalt;  lamp  black  and 
a  mixture  of  lamp  black  with  mica  scales  is  also  used 
with  great  success,  especially  in  portable  refrigerating 
chambers,  refrigerator  cars  and  the  like,  as  it  will  not 
pack  from  jolting,  owing  to  its  lightness  and  elasticity, 
and  it  also  withstands  moisture  very  well. 

REFRIGERATING  CONTENTS. 

If  the  amount  of  refrigeration  required  to  replace 
the  cold  lost  by  the  transmission  of  walls,  windows,  ceil- 
ings, etc.,  has  been  determined  upon,  the  refrigeration 
required  to  reduce  the  temperature  of  the  goods  placed 
in  storage  to  that  of  the  storage  room  is  next  to  be 
ascertained. 

If  p,  Pi,  P2,  etc.,  be  the  number  of  pounds  of  differ- 
ent produce  introduced  daily  into  the  storage  room  and 
s,  st,  s2,  etc.,  their  respective  specific  heat,  t  their  tem- 
perature and  tl  the  temperature  of  the  storage  room,  we 
find  the  amount  of  refrigeration,  .R, in  B.T.  units  required 
daily  to  cool  the  ingoing  product  after  the  formula: 

R  =  (p  s  +  p±  s,  +  p2  s,)  (t  —  tt)  B.  T.  units, 
or,  expressed  in  tons  of  refrigeration : 

•R  —  (Vs+Pi  si  +  P2  sz)  (t  —  t±)  t 

284000 

The  specific  heat  of  some  of  the  articles  frequently 
placed  in  cold  storage  may  be  found  in  the  following  table: 

SPECIFIC  HEAT  AND  COMPOSITION  OF  VICTUALS. 


*8 

14 

S* 

W>^ 

&M 

JS  a 

K    N     • 

Water. 

Solids. 

S«3 

£*& 

43  5J'c3 

§|* 

Z£° 

OQ  c3 

2£u> 

o  O  a 

ir 

§£o 

3o 

Lean  beef  

72  00 

28  00 

0.77 

0.41 

102 

Fat  beef  

51.00 

49.00 

0.60 

0.34 

72 

Veal  

63  00 

37.00 

0.70 

0.39 

90 

Fat  pork 

39  00 

61  00 

0  51 

0  30 

55 

Eggs  

70  00 

30  00 

0.76 

0.40 

100 

Potato  

T4  00 

26  00 

0  80 

0  42 

105 

91.00 

9.00 

.0.93 

0.48 

129 

Carrots  .............. 

83  00 

17.00 

0.87 

0.45 

118 

69  25 

30  75 

0  68 

0  38 

84 

Milk  

87  50 

12.60 

0.90 

0.47 

124 

Oyster            .... 

80  38 

19  62 

0  84 

0.44 

114 

Whitefisn  

78.00 

22.00 

0.82 

0.43 

111 

Eels          

62  07 

37.93 

0.69 

0.38 

88 

76.62 

23.38 

0.81 

0.42 

108 

72  40 

27.60 

0.78 

0.41 

Chicken              . 

73  10 

26  30 

0-80 

0.42 

COLD  STOKAGE.  183 

CALCULATION  OF  SPECIFIC  HEATS  OF  VICTUALS. 

The  specific  heats  in  the  fifth  column  of  the  forego- 
ing table  is  calculated  after  the  formula 

s=_«_±  0.2^=0.008  a  +  0.20 
1UU 

in  which  formula  s  signifies  the  specific  heat  of  a  sub- 
stance containing  "  a"  per  cent  of  water  and  "6"  per 
cent  of  solid  matter;  0.2  is  the  value  which  has  been  uni- 
formly assumed  to  represent  the  specific  heat  of  the  solid 
constituents  of  the  different  articles  in  question.  If  the 
articles  are  cooled  below  freezing,  which  takes  place  be- 
low 32°  F.,  the  specific  heat  changes,  owing  to  the  fact 
that  the  specific  heat  of  frozen  water  is  only  a^out  half 
of  that  of  liquid  water.  In  conformity  with  this  fact, 
and  considering  that  the  specific  heat  of  the  solid  mat- 
ter is  not  apt  to  change  under  these  circumstances,  we 
find  the  specific  heat,  s',  of  the  same  articles  in  a  frozen 
condition  after  the  following  formula  : 


and  in  this  way  I  have  obtained  the  figures  in  the  sixth 
column  of  the  above  table. 

The  figures  in  the  last  column,  showing  the  latent 
heat  of  freezing,  have  been  obtained  by  multiplying  the 
latent  heat  of  freezing.  water,  which  is  142  B.  T.  U.  by 
the  percentage  of  water  contained  in  the  different  ma- 
terials considered.  In  this  manner  the  specific  heat  for 
other  articles  may  be  readily  calculated. 

For  still  more  approximate  determination  we  may 
assume  that  the  specific  heat  of  all  kinds  of  produce  is 
about  0.8.  On  this  basis  the  amount  of  refrigeration,  .R, 
required  to  reduce  the  temperature  of  the  produce  to 
that  of  the  refrigerating  room  is  — 
B=P(t—t1)  0.8  units. 

And  expressed  in  tons= 

E  =     35500Q    tons  of  refrigeration. 

P  being  the  total  weight  of  the  produce  introduced 
daily. 

FREEZING  GOODS  IN  COLD  STORAGE. 

If,  in  addition  to  the  refrigeration  of  the  goods  to  be 
stored  the  same  have  to  be  actually  frozen  and  cooled 
clown  to  a  certain  temperature  below  freezing,  the  re- 
frigeration as  calculated  in  the  foregoing  paragraph 


184  MECHANICAL   REFRIGERATION. 

must  be  corrected,  for  the  water  contained  in  the  goods 
must  be  frozen,  which  requires  an  additional  amount  of 
refrigeration.  On  the  other  hand,  the  specific  heat  of 
the  frozen  water  being  one-half  of  that  of  water,  this 
circumstance  lessens  somewhat  the  amount  of  refrigera- 
tion required  below  freezing  point.  Therefore  if  p  rep- 
resents the.  number  of  pounds  of  water  contained  in  a 
daily  charge  for  cold  storage  to  be  chilled  and  reduced  to 
a  temperature,  tt,  the  amount,  R,  found  by  the  foregoing 
rules  must  be  corrected  by  adding  to  it  an  amount  of 
refrigeration  equivalent  to— 

p  (126  +  0.5^)  units. 

CONDITIONS  FOR  COLD  STORAGE. 

For  the  preservation  of  perishable  goods  by  cold 
storage  the  teipperature  is  the  main  factor,  although 
other  conditions,  such  as  clean,  dry,  well  ventilated  rooms 
and  pure  air,  are  of  paramount  importance.  Humidity  is 
almost  as  important  as  temperature.  Extreme  cold  tem- 
perature will  react  on  certain  goods  like  eggs,  fruits,  etc  , 
so  that  when  taken  out  the  change  of  temperature  will 
deteriorate  their  quality  quickly.  Hence  the  conditions 
under  which  articles  must  pass  from  cold  storage  to  con- 
sumption are  often  of  as  vital  importance  as  the  cold 
storage  itself,  for  which  reason  special  rules  must  be 
followed  in  special  cases. 

MOISTURE  IN  COLD    STORAGE. 

Besides  the  temperature  in  a  cold  storage  room  the 
degree  of  moisture  is  of  considerable  importance. 

It  is  neither  necessary  nor  desirable  that  the  storage 
room  should  be  absolutely  dry;  on  the  contrary,  it  may  ba 
too  dry  as  well  as  it  may  too  damp.  If  the  room  is  tow 
dry  it  will  favor  the  shrinkage  and  drying  out  ot  certain 
goods.  If  the  room  is  too  damp  goods  are  liable  to  spoil 
and  become  moldy,  etc.  For  this  reason  the  moisture 
should  always  be  kept  below  the  saturation  point.  This 
condition  can  be  ascertained  by  the  hygrometic  methods 
described  in  the  chapter  treating  on  water  and  steam. 

There  is  little  danger  that  the  rooms  will  ever  be  too 
dry;  on  the  other  hand,  they  are  not  required  to  be  abso- 
lutely dry,  and  as  to  chemical  dryers,  such  as  chloride 
of  calcium,  oatmeal,  etc.,  they  are  probably  superflu* 
ous,  with  proper  ventilation  and  refrigerating  machinery 
properly  applied. 


STORAGE.  185 

Generally  the  artificial  drying  of  air  is  considered 
superfluous  in  coM  storage,  as  the  air  is  kept  sufficiently 
dry  by  the  condensation  that  forms  on  the  refrigerating 
pipes.  In  this  way  the  moisture  exhaled  by  fruits,  etc., 
is  also  deposited.  Special  care,  however,  is  to  be  taken 
to  remove  the  ice  from  the  coils  from  day  to  day  as  it 
forms,  in  which  case  it  is  readily  removable.  Chemical 
dryers  are  seldom  used  in  storage  houses  refrigerated  by 
artificial  refrigeration.  Freshly  burnt  lime  is  sometimes 
used  in  egg  rooms. 

In  cold  storage  houses  operated  by  natural  ice,  chem- 
ical or  physical  absorbents,  such  as  oatmeal,  burned  lime, 
chloride  of  calcium  and  chloride  of  magnesium  are  fre- 
quently used.  The  latter  substance  is  the  principal  con- 
stituent of  the  waste  bittern  of  salt  works,  which  is 
sometimes  used  for  drying  air  in  the  cold  storage  of  fruit. 

The  waste  bittern  is  spread  out  on  the  entire  sur- 
face of  the  floor,  and,  if  needed,  on  additional  surfaces 
above  it.  One  square  foot  of  well  exposed  bittern,  either 
in  the  dry  state  or  state  of  inspissated  brine,  will  be 
enough  to  take  up  the  moisture  arising  from  two  to  six 
bushels  of  fruit,  varying  according  to  its  condition  of 
greenness  or  ripeness.  The  floors  of  the  preserving  room 
should  be  level,  so  that  the  thick  brine  running  from  the 
dry  chloride  may  not  collect  in  basins,  but  spread  over 
the  largest  surface.  The  moisture  from  the  fruit  taken 
up  by  the  absorbent  varies  from  about  three  to  ten  gal- 
lons for  every  1,000  bushels  of  fruit  weekly.  The  spent 
chlorides  or  the  spent  waste  bittern  may  be  revived  by 
evaporation,  by  which  they  are  boiled  down  to  a  solid 
mass  again. 

The  waste  bittern  is  also  used  as  a  crude  hydrometer 
by  dissolving  one  ounce  of  the  same  in  two  ounces  of 
water  and  by  balancing  the  shallow  tin  dish  containing 
this  mixture  on  a  scale  placed  in  the  cold  storage  room. 
If  the  scale  keeps  balanced,  it  indicates  the  proper  state  of 
dryness,  but  if  the  weight  of  the  mixture  increases,  the 
moisture  in  the  room  is  increasing  and  the  means  for 
keeping  the  air  dry  should  be  put  in  operation. 

DRY  AIR  FOR  REFRIGERATING  PURPOSES. 

To  produce  a  dry  air  by  mechanical  means  St.  Clair 
considers  the  entire  absence  of  any  condensing  or  refrig- 
erating surface  in  the  space  to  be  refrigerated  absolutely 


186  MECHANICAL  REFRIGERATION- 

necessary.  The  rapid  circulation  of  the  air  in  the  room  is 
also  of  vital  importance;  and  in  such  circulation  no  con- 
tact of  the  incoming  cold  air  with  the  outgoing  warm  air 
to  cause  condensation  is  the  result  aimed  at.  To  insure 
these  conditions  he  places  the  refrigerator  at  the  highest 
point,  and  has  communicating  air  shafts  from  the  bottom 
of  the  same  to  the  rooms  to  be  cooled.  Like  shafts  ascend 
from  the  top  of  the  rooms  cooled  to  top  of  the  refrigerator. 
The  refrigerating  coils  in  the  refrigerator  are  kept  at  a 
temperature  of  zero  to  15°  below,  and  a  small  stream  of 
strong  brine  is  allowed  to  drip  over  the  coils  to  a  pan 
underneath,  being  pumped  back  to  the  upper  drips  as  fast 
as  deposited.  This  brine  will  have  a  temperature  rang- 
ing from  zero  to  4°  below.  The  action  is  said  to  be 
simple  and  effective;  all  moisture  is  either  condensed  or 
frozen  instantly  as  it  comes  in  contact  with  such  low 
temperature,  and  an  absolutely  dry  air  descends  in  the 
air  shafts  to  the  rooms  to  be  cooled. 

VENTILATION  OF  COLD  STORAGE  ROOMS. 

The  foul  air  in  storage  rooms  is  removed  by  ventila- 
tion, which  is  effected  in  various  ways.  Frequently  the 
change  of  air  brought  about  by  opening  doors,  etc.,  is 
considered  sufficient;  in  some  cases  windows  are  opened 
from  time  to  time.  Ventilating  shafts  located  in  the  ceil- 
ing of  storage  rooms  are  also  often  used  as  means  to  effect 
a  change  of  air.  A  small  rotary  fan,  located  in  the  engine 
room  and  connected  with  the  storage  rooms  by  galvanized 
iron  pipes,  provided  with  gates  or  valves,  is  a  very  effi- 
cient device  to  remove  foul  air. 

Where  fans  cannot  be  applied  for  want  of  motive 
power  or  other  reasons  a  ventilating  shaft,  if  properly 
constructed,  will  answer  every  purpose,  and  is  much  less 
expensive  to  operate.  The  air  ducts,  or  pipes,  should  be 
located  in  the  hallways,  and  connection  made  thence  to 
each  room  through  the  side  wall  near  the  ceiling,  and 
some  suitable  device  should  be  arranged  on  the  end  of 
the  pipe  extending  into  the  cooling  room  to  regulate  the 
amount  of  ventilation.  The  several  air  ducts  leading 
from  the  various  hallways  should  have  a  common  ending, 
and  connection  made  thence  to  the  smoke  stack.  The 
strong  up  draft  from  the  furnace  insures  ample  ventila- 
tion from  rooms  at  all  times,  provided  that  the  pipes  are 
made  air  tight  and  large  enough  for  the  purpose. 


COLD  STORAGE.  187 

The  simple  expedient  of  a  ventilating  shaft  extend- 
ing just  outside  of  the  building  without  being  raised  to  a 
considerable  height,  or  some  provision  made  to  artifi- 
cially produce  a  draft,  often  proves  inoperative  as  a  means 
of  ventilating  refrigerating  rooms,  because  the  air  in  the 
rooms,  becoming  cold,  settles  to  the  floor  and  escapes 
through  crevices  about  the  doors  or  when  the  doors  are 
opened,  causing  a  down  draft,  and  in  many  cases  over- 
balancing the  uptake  of  the  ventilating  pipe. 

FOBCBD  CIRCULATION. 

Of  the  various  recent  devices  for  forced  circulation 
and  the  drying  of  air  in  cold  storage,  most  are  based  on 
the  principle  of  St.  Clair  delineated  in  the  foregoing 
paragraph.  It  may  also  be  combined  with  any  system  of 
artificial  ventilation  which  may  be  brought  about  by 
fans,  ventilators,  etc.  The  introduction  of  air  cooled  a 
few  degrees  below  the  temperature  of  the  storage  room 
(by  drawing  the  air  over  refrigerated  surface,  as  is  done 
in  the  St.  Clair  and  similar  systems)  insures  dry  ventila- 
tion. 

VELOCITY  OF  AIB. 

If,  as  in  the  St.  Clair  system  of  forced  circulation, 
the  air  after  having  been  cooled  (and  dried)  by  being 
passed  over  the  refrigerating  coils  located  in  the  top  part 
of  the  storage  rooms,  falls  down  from  the  bottom  of  the 
coil  through  a  shaft  or  shafts  to  the  bottom  of  the  room, 
while  the  hot  air  from  the  top  of  the  room  ascends  to  the 
top  of  the  coil  by  shafts  or  a  shaft,  the  velocity  of  the 
air  current  thus  produced  by  a  difference  in  temperature, 
or  rather  by  a  difference  in  gravity  due  thereto,  may  be 
expressed  by  the  following  formula: 


V=  1346          ~°  (1X0.0021 
V       ^o 

In  this  formula  T  and 
degrees  absolute  Fahrenheit)  of  the  air  in  the  hot  and 
cold  air  shafts  respectively,  which  are  supposed  to  have 
the  same  sectional  area,  and  Fis  the  velocity  with  which 
the  air  moves  through  the  shafts  in  feet  per  second. 

NUMERICAL  RULES  FOR  MOISTURE. 

The  proper  degree  of  humidity  in  cold  storage  rooms, 
especially  also  for  the  storage  of  eggs  (to  avoid  mold 
and  shrinkage  at  the  same  time)  is  of  the  utmost  impor- 
tance, and  Cooper  finds  that  the  relative  humidity  should 


188  MECHANICAL  REFRIGERATION. 

differ  with  the  temperature  at  which  the  rooms  are  kept. 
Thus  a  room  kept  at  28°  F.  should  have  a  relative  hu- 
midity of  80  per  cent,  while  a  room  kept  at  40°  F.  should 
have  a  humidity  of  only  53  per  cent,  and  intermediate 
degrees  of  humidity  for  intermediate  temperatures.  At 
least  one  correct  normal  thermometer  (to  correct  the 
others  by)  should  be  kept  in  each  cold  storage  plant. 

DISINFECTING    COLD   STORAGE  ROOMS. 

Meat  rooms  and  other  cold  storage  rooms  may  be  dis^ 
infected  if  necessary  by  formaldehyde  vapors,  which 
are  produced  by  burning  wood  spirit  in  an  ordinary  spirit 
lamp,  the  wick  of  which  is  covered  by  a  platinum  wire 
screen,  in  the  form  and  size  of  a  thimble,  to  make  it  only 
glow,  and  not  burn  with  a  flame.  Special  lamps  are  made 
also  for  this  purpose. 

COLD   STORAGE  TEMPERATURES. 

Generally  speaking,  the  temperature  of  cold  storage 
rooms  is  about  34°  F.  For  chilling  the  temperature  of 
the  room  it  is  generally  brought  down  to  30°  F.,  and  in 
the  case  of  freezing  goods  from  10°  F.  to  0°  F. 

The  temperatures  and  other  conditions  considered 
best  adapted  for  the  cold  storage  of  different  articles  of 
food,  provisions,  etc.,  have  been  compiled  in  the  follow- 
ing paragraphs,  which  reflect  the  views  of  practical  and 
successful  cold  storage  men  as  expressed  by  them  in  Ice 
and  Refrigeration: 

STORING  FRUITS. 

The  temperatures  for  storing  fruits  are  given  in  the 
following  table: 

FRUIT.                                REMARKS.  °F 

Apples 30-40 

Bananas 34-36 

Berries,  fresh For  three  or  four  days 34-36 

Canteloupes Carry  only  about  three  weeks 32 

Cranberries 33-34 

Dates,  figs,  etc  » 34 

Fruits,  dried  35-40 

Grapes 32-40 

Lemons 36-45 

Oranges 36 

Peaches 35-45 

Pears 33-36 

W  atermelons Carry  only  about  three  weeks 32 

In  general,  green  fruits  and  vegetables  should  not  be 
allowed  to  wither.  Citrus  fruits  sheuld  be  kept  dry  until 
the  skin  yields  its  moisture,  then  the  drying  process 
should  be  immediately  checked.  For  bananas  no  rule 
can  be  made ;  the  exigencies  of  the  market  must  govern 
the  ripening  process,  which  can  be  manipulated  almost 
at  will- 


COLE  STORAGE!.  189 

Fruits,  especially  tender  fruits,  should  be  placed  in 
cold  storage,  just  when  they  are  ripe.  They  will  keep 
better  than  if  put  in  when  they  are  not  fully  ripe. 

Pears  will  stand  as  low  a  temperature  as  33°.  Sour 
fruit  will  not  bear  as  much  cold  as  sweet  fruit.  Catawba 
grapes  will  suffer  no  harm  at  26°,  while  36°  will  be  as 
cold  as  is  safe  for  a  lemon. 

The  spoiling  of  fruit  at  temperatures  below  40°  P.  is 
due  to  moisture. 

ONIONS. 

Onions,  if  sound  when  placed  in  cold  storage,  can  be 
carried  several  months  and  come  out  in  good  condition. 
It  is  important  that  the  onions  be  as  dry  as  possible  when 
put  into  cold  storage.  If  they  can  be  exposed  to  a  cool, 
dry  wind,  they  will  lose  much  of  their  moisture.  They 
are  usually  packed  in  ventilated  packages  or  crates.  It 
is  claimed,  however,  that  they  will  keep  all  right  in 
sacks,  if  the  sacking  is  not  too  closely  woven,  and  stored 
in  a  special  way,  being  arranged  in  tiers  so  the  air  has 
free  access.  Authorities  differ  as  to  the  best  tempera- 
ture at  which  to  keep  the  onions,  the  range  being  from 
30°  to  35°  P.  But  32°  to  33°  seems  to  be  generally  pre- 
ferred. The  rooms  should  be  ventilated  and  have  a  free 
circulation  of  dry  air.  Onions  should  not,  of  course,  be 
stored  in  rooms  with  other  goods.  When  the  onions  are 
removed  the  rooms  should  be  well  aired,  thoroughly 
scrubbed  and,  after  the  walls,  ceiling  and  floor  are  free 
from  moisture,  should  be  further  purified  and  sweetened 
by  the  free  use  of  lime  or  whitewash;  and  a  good  coat  of 
paint  or  enamel  paint  would  be  advantageous,  after 
which  the  rooms  can  be  used  for  the  storage  of  other 
goods,  though  some  practical  cold  storage  men  are  of  the 
opinion  that  such  rooms  should  not  afterward  be  used  for 
the  storage  of  eggs,  butter  or  other  articles  so  sensitive 
and  susceptible  to  odors,  but  should  be  set  aside  for  the 
storage  of  such  goods  as  would  not  be  injured  by  foreign 
odors. 

Attempts  have  been  made  to  kiln  dry  onions,  but 
this  was  found  impracticable,  owing  to  the  fact  that  the 
extreme  heat  required  to  penetrate  the  tough  outer  skin 
of  the  onion  caused  it  to  soon  decay.  Experiments  have 
also  been  made  with  evaporating  onions  after  removing 
the  outer  skin,  but  this  was  also  unsuccessful.  There  is 
GO  difficulty,  however,  in  keeping  onions  in  cold  storage 


190  MECHANICAL  REFRIGERATION. 

for  six  or  seven  months  and  having  them  come  out  in 

perfect  condition,  if  the  above  suggestions  are  followed. 

PEARS. 

Pears,  like  other  tender  fruit,  should  be  placed  in 
cold  storage  when  still  firm,  and  before  the  chemical 
changes  which  cause  the  ripening  have  set  in  ;  and  they 
must  be  handled  very  carefully.  The  temperature  at 
which  to  store  them  is  from  33°  to  40°  F.  The  pears 
after  having  been  kept  in  cold  storage  will  spoil  very 
rapidly  after  coming  out,  and  should  be  consumed  as 
short  a  time  thereafter  as  may  be. 

Pears  should  be  picked  as  soon  as  the  stem  will 
readily  part  from  the  twig,  and  before  any  indications 
of  ripeness  appear ;  and,  as  in  the  case  of  apples,  should 
immediately  be  placed  in  storage,  but  the  temperature 
should  not  be  as  low  as  for  apples. 

Few  kinds  of  pears  can  be  kept  as  late  as  April  and 
May;  even  after  January  there  is  considerable  risk.  The 
temperature  should  be  between  33°  and  40°,  but,  as  for 
all  winter  storage  goods,  must  be  constant  and  uniform, 
for  which  reason  the  rooms  should  have  heating  as  well 
as  chilling  pipe.  The  paper  wrapper  will  best  protect 
them  from  touching  each  other  in  storage. 
LEMONS. 

The  best  storage  temperature  for  lemons  is  allowed 
to  be  45°  and  below,  but  below  36°  F.  they  are  liable  to 
be  injured,  if  kept  at  that  temperature  for  any  length  of 
time.  The  acid,  which  is  the  principal  ingredient  ot 
lemons,  is  decomposed,  and  those  containing  the  least 
acid  will  stand  the  least  cold.  Lemons  should  not  be  ex- 
pected to  keep  good  in  cold  storage  over  four  months. 
Lemons  stored  during  the  first  three  months  of  the  year 
are  said  to  hold  good  for  at  least  five  months,  but  if  stored 
later  it  is  more  difficult  to  preserve  them. 
GRAPES. 

Grapes  for  cold  storage  must  be  well  selected  and 
very  carefully  packed.  No  crushed  or  bruised  or  partly 
decayed  berries  are  allowable;  a  whole  lot  may  be  tainted 
by  a  single  berry.  Grapes  lose  much  in  flavor  and  taste 
in  cold  storage.  Malagas  hold  their  flavor  best,  and  will 
last  till  Christmas  and  even  longer,  but  the  Concord  and 
other  softer  grapes  will  not  hold  out  after  Thanksgiving 
day,  as  a  rule.  The  best  temperature  is  from  33°  to  40°. 


COLD  STORAGE.  191 

At  the  latter  temperature  the  flavor  appears  to  suffer 
less,  especially  with  the  Concord,  and  the  lower  tem- 
perature has  more  effect  on  the  Concord  than  on  the 
Malaga,  it  appears,  generally  speaking. 
APPLES. 

Apples  may  be  kept  either  in  barrels  or  boxes  or  in 
bulk,  it  is  said,  with  equally  good  results.  The  barrels, 
etc.,  if  kept  in  storage  for  any  length  of  time,  must  be 
refilled  to  make  up  for  shrinkage,  before  being  put  on 
the  market.  Opinions  as  to  best  temperature  for  apples 
vary  all  the  way  from  30°  to  40°.  The  latter  temperature 
should  not  be  exceeded  in  any  case.  If  the  air  in  cold 
storage  is  too  dry  it  wilts  the  apples,  and  if  it  is  too  damp 
it  bursts  and  scalds  apples,  especially  if  the  temperature 
is  not  low  enough.  The  so  called  "  Rhode  Island  Green- 
ing" seems  to  be  most  susceptible  to  scalds.  Apples 
should  be  picked  early  and  put  in  cold  storage  with  the 
least  possible  delay.  Apples  when  stored  in  barrels 
should  not  be  stored  on  ends,  but  preferably  on  their 
sides.  A  temperature  of  33°  is  considered  most  favor- 
able by  some. 

In  storing  apples  eight  to  ten  cubic  feet  storage  room 
space  is  allowed  per  barrel,  and  twenty  to  twenty-five 
tons  daily  refrigerating  capacity  per  10,000  barrels. 

STORING  VEGETABLES. 

ARTICLES.  °  F. 

Asparagus 84 

Cabbage 32-34 

Carrots 33-34 

Celery 83-35 

Driedbeans 33-40 

Dried  corn 35 

Dried  peas 40 

Onions 82-34 

Parsnips 33-34 

Potatoes 34-36 

Sauerkraut 35-38 

Sweet  corn 35 

Tomatoes 34-35 

Asparagus,  cabbage,  carrots,  celery,  are  carried  with 
little  humidity;  parsnips  and  salsify,  same  as  onions  and 
potates,  except  that  they  may  be  frozen  without  detri- 

FERMENTED  LIQUORS. 

ARTICLES.  °  F, 

Beer,  ale,  porter,  etc 83-42 

Beer,  bottled 46 

Cider 30-40 

Ginger  ale 36 

Wines 40-45 

Clarets., ..,,* 45-50 


192  MECHANICAL  REFRIGERATION. 

The  temperatures  at  which  these  articles  are  to  be 
kept  in  storage  is  of  course  not  the  temperature  at  which 
they  should  be  dealt  out  for  consumption.  Beer,  ale  and 
porter  should  not  be  offered  for  consumption  at  a  temper- 
ature below  52°  F.,  and  temperatures  between  57®  and  61° 
are  even  preferable  on  sanitary  grounds,  which,  however, 
are  often  disregarded  to  insure  a  temporarily  refreshing 
palate  sensation. 

STORING  FISH  AND  OYSTERS. 

Fish  if  previously  frozen  should  be  kept  at  25°  after 
being  frozen.  Oysters  should  not  be  frozen.  The  follow- 
ing temperatures  are  given: 

ARTICLES.  °  F. 

Driedfish 35 

Freshfish.    25-30 

Oysters 33-40 

Oysters  in  shell 40 

Oysters  in  tubs 35 

A  successful  firm  describes  the  freezing  of  fish  as 
follows: 

When  the  fish  are  unloaded  from  the  boats  they  are 
first  sorted  and  graded  as  to  size  and  quality.  These  are 
placed  in  galvanized  iron  pans  twenty- two  inches  long, 
eight  inches  wide  and  two  and  a  half  inches  deep,  covered 
with  loosely  fitting  lids,  each  pan  containing  about  twelve 
pounds.  The  pans  are  then  taken  to  the  freezers.  These 
are  solidly  built  vaults  with  heavy  iron  doors,  resembling 
strong  rooms,  and  filled  with  coils  of  pipes  so  arranged 
as  to  form  shelves.  On  these  shelves  the  pans  are  placed, 
and  as  one  feature  of  the  fixtures  is  economy  of  space, 
not  an  inch  is  lost.  The  pans  are  kept  here  for  twenty- 
four  hours  in  a  temperature  at  times  as  low  as  16°  below 
zero.  Each  vault  or  chamber  has  a  capacity  of  two  and 
a  half  tons,  and  there  are  sixteen  of  them,  giving  a  total 
capacity  of  forty  tons,  which  is  the  amount  of  fish  that 
can  be  frozen  daily  if  required. 

On  being  taken  out  of  the  sharp  freezers  the  pans 
are  sent  through  a  bath  of  cold  water,  and  when  the  flsb 
are  removed  they  are  frozen  in  a  solid  cake.  These  cakes 
are  then  taken  to  the  cold  storage  warehouse,  which  is 
divided  into  chambers  built  in  two  stories,  almost  the 
same  as  the  sharp  freezers.  The  cakes  of  fish,  as  hard  as 
stone,  are  packed  in  tiers  and  remain  in  good  condition 
ready  for  sale.  It  is  possible  to  preserve  them  for  an  indefi- 
nite time,  but  as  a  rule  frozen  fish  are  only  kept  for  a  sea- 
son of  from  six  to  eight  months.  They  are  frozen  in  the 
spring  and  fall  when  there  is  a  surplus  of  fish,  and  sold 


COLD  STORAGE.  19'j 

generally  in  the  winter  or  in  the  close  season  when  fresh 
fish  cannot  be  obtained. 

For  shipment,  flsh  may  be  packed  in  barrels  after 
the  following  directions:  Put  in  a  Shovelful  of  ice  at  the 
bottom  of  the  barrel,  and  be  always  careful  to  see  that 
auger  holes  are  bored  into  the  bottom  of  the  barrels,  to 
let  the  water  leak  out  as  fast  as  it  is  produced  by  the 
melting  ice.  After  putting  in  a  shovelful  of  fine  ice, 
crushed  by  an  ice  mill,  put  in  about  fifty  pounds  of  fish; 
then  another  shovelful  of  ice  on  top  of  the  fish,  etc., 
until  the  barrel  is  full,  always  leaving  space  enough  on 
the  top  of  the  barrel  to  hold  about  three  shovelsf ul  of 
ice.  By  shovels,  scoop  shovels  are  meant. 

Oysters  are  said  to  keep  six  weeks  safe  at  40°.  In  one 
instance  they  have  been  kept  ten  weeks  at  this  tempera- 
ture for  an  experiment. 

STORING  BUTTER. 

Butter  is  preserved  both  ways  :  by  keeping  the  same 
at  the  ordinary  cold  storage  temperatures,  and  also  by 
freezing.  Both  processes  have  given  satisfactory  results, 
but  it  appears  that  those  obtained  by  actual  freezing  are 
quite  superior,  the  flavor  and  other  qualities  of  the 
butter  being  perfectly  preserved  by  the  freezing.  To 
obtain  the  best  results  butter  should  be  frozen  at  a  tem- 
perature of  20°  and  the  variation  should  not  be  over  2C 
to  3°.  For  long  storage,  however,  butter,  like  fish,  should 
be  frozen  quickly  at  a  temperature  of  from  5°  to  10°,  and 
subsequently  it  should  be  kept  at  about  20-  F.  Ash  and 
spruce  tubs  make  the  best  packages  for  butter. 

As  regards  thawing  it,  it  is  simply  taken  from  the 
freezer,  as  in  the  case  of  ordinary  cold  storage  goods,  with- 
out paying  any  attention  to  the  thawing  out  process.  The 
thawing  comes  naturally,  and  the  effect  that  it  has  upon 
the  butter  is  to  give  it  a  higher  and  quicker  flavor  when 
thawed  out  than  when  frozen.  When  selling  frozen  goods 
it  is  sometimes  necessary  to  let  them  stand  out  a  little 
time  in  order  to  get  the  frost  out  of  the  butter;  particu- 
larly so  in  the  case  of  high  grade  goods,  for  the  thawing 
develops  the  flavor.  June  butter  is  considered  the  best 
for  packing  and  storage.  It  is  essential  to  exclude  the 
air  from  butter  while  being  held  in  cold  storage,  hence 
cooperage  must  be  the  best,  and  soaked  in  brine  for 
twenty -four  hours.  If  the  top  of  the  butter  is  well  cov- 
ered with  brine,  a  temperature  of  33°  to  35°  will  answer, 


134  MECHANICAL  REFRIGERATION. 

For  ordinary  cold  storage  of  butter  and  similar  articles, 
the  following  temperatures  are  given: 

ARTICLES.  °  P. 

Butter 32-35 

Butterine 35 

Oleomargarine 35 

STORING  CHEESE. 

The  best  temperature  for  the  storage  of  cheese  is 
generally  considered  32°  to  33°,  and  should  not  vary  more 
than  1°.  Cheese  should  not  have  been  subjected  to  any 
high  temperature  before  being  placed  in  cold  storage. 

Cheese  should  be  well  advanced  in  ripening  before  it 
is  placed  in  cold  storage,  to  avoid  bad  smell  in  the  house. 
It  generally  enters  the  cold  storage  room  in  June  and 
July,  and  leaves  by  the  end  of  January,  sooner  or  later 
when  needed.  It  will  keep  much  longer,  however,  over 
a  year  when  needed.  It  must  be  kept  frem  freezing. 
If  frozen,  it  must  be  thawed  gradually,  and  consumed 
thereafter  as  soon  as  possible,  or  otherwise  it  will  spoil 
internally.  The  humidity  of  the  room  must  keep  the 
cheese  from  shrinking  and  cracking,  but  the  room  must 
not  be  damp  either,  otherwise  mold  will  set  in. 
MILK. 

Milk  is  not  as  a  rule  kept  in  cold  storage  except  for  a 
short  period.  It  has  been  proposed,  however,  to  con- 
centrate milk  by  a  freezing  process,  by  which  part  of  the 
water  in  the  ice  is  converted  into  ice.  The  ice  is  allowed 
to  form  on  the  surface  of  the  pans,  which  are  placed  in 
cold  rooms,  and  the  surface  of  the  ice  is  broken  fre- 
quently, to  present  a  fresh  surface  for  freezing. 

EGGS. 

Eggs  should  be  carefully  selected  before  being  placed 
in  cold  storage,  and  every  bad  one  picked  out  by  can- 
dling. The  best  temperature  for  storing  eggs  is  between 
32°  and  33°  F.  As  eggs  are  very  sensitive  and  will  absorb 
bad  odors,  etc.,  it  is  not  advisable  to  store  them  together 
with  cheese  or  other  products  exhaling  odors. 

For  some  purposes  the  contents  of  eggs  may  be 
stored  in  bulk.  In  this  case  the  eggs  are  emptied  into 
tin  cans  containing  about  fifty  pounds  and  stored  for  any 
length  of  time  at  30°  F.  They  must  be  used  quickly 
after  thawing. 

Eggs  are  generally  placed  in  cold  storage  in  April 
and  early  May;  later  arrivals  will  not  keep  as  well. 
They  are  seldom  kept  longer  than  February.  The  tern- 


COLD  STORAGE.  195 

perature  best  suited  for  eggs  is  supposed  to  be  between 
31°  and  34°  by  American  packers,  but  English  dealers 
claim  that  40°  to  45°  is  equally  good.  The  humidity  of 
the  air  in  the  cold  storage  room  has  doubtless  a  great 
bearing  on  this  question. 

Eggs  which  have  been  stored  at  30°  must  be  used 
soon  after  leaving  storage,  while  eggs  kept  at  35°  to  40° 
will  keep  nice  for  a  longer  time,  as  the  germ  has  not  been 
killed  in  the  latter,  and  consequently  they  taste  fresh. 
Eggs  for  the  market,  especially  those  to  go  in  cold  stor- 
age, must  not  have  been  washed.  Washed  eggs  have  a 
dead  and  lusterless  looking  shell,  looking  like  burned 
bone  through  a  magnifying  glass. 

It  is  also  recommended  that  eggs  in  cold  storage 
should  be  reversed  at  least  twice  weekly. 

The  age  of  eggs  may  be  approximately  determined  by 
the  following  method,"  based  upon  the  decrease  in  the 
density  (through  loss  of  moisture)  of  the  eggs  as  they 
grow  old:  Dissolve  two  ounces  of  salt  in  a  pint  of  water, 
and  when  a  fresh  egg  is  placed  in  the  solution  it  will  im- 
mediately sink  to  the  bottom  of  the  vessel.  An  egg 
twenty-four  hours  old  will  sink  below  the  surface  of  the 
water,  but  not  to  the  bottom  of  the  vessel.  An  egg  three 
days  old  will  swim  in  the  liquid,  and  when  more  than 
three  days  old  will  float  on  the  surface.  The  older  the 
egg  the  more  it  projects  above  the  surface,  an  egg  two 
weeks  old  floating  on  the  surface  with  but  very  little  of 
the  shell  beneath  the  water. 

Experiments  have  been  made  for  the  preservation  of 
eggs  by  dipping  them  in  chemicals,  but  with  no  notable 
success.  It  is  reported  that  when  preserved  in  lime  water, 
or  in  a  solution  of  waterglass  or  by  coating  with  vaseline 
they  will  keep  for  eight  months,  but  doubtless  not  with- 
out some  detrimental  alteration  in  taste  and  flavor. 

DRYING  OF  EGG  ROOMS,  ETC. 

For  the  drying  of  egg  rooms,  etc.,  Mr.  Cooper  recom- 
mends supporting  a  quantity  of  chloride  of  calcium 
above  the  cooling  coils,  over  which  the  air  is  circulated 
by  mechanical  means.  The  brine  formed  by  the  absorp- 
tion of  moisture  by  the  chloride  of  calcium  will  then 
trickle  down  over  the  pipes  and  thereby  effectually  pre- 
vent any  formation  of  frost  on  the  pipes,  and  therefore 
keep  them  at  their  maximum  efficiency  at  all  times, 
The  air,  in  passing  over  the  brine  moistened  surface  of 


196  MECHANICAL  REFRIGERATION. 

the  coils,  is  purified,  and  the  briiie,  after  falling  to  the 
floor  of  the  cooling  room,  goes  to  the  sewer,  and  no  fur- 
ther contamination  takes  place.  The  re-use  of  the  salt 
after  redrying  is  objected  to  by  some  on  account  of  these 
contaminations;  but  it  seems  to  us  that  they  will  be  ren- 
dered entirely  harmless  if  the  salt  is  dried  at  a  sufliciently 
high  temperature,  and  this  can  hardly  be  avoided  if  the 
water  is  all  driven  off,  to  do  which  requires  calcination 
at  a  tolerably  high  temperature,  a  temperature  which  ?e 
far  above  that  at  which  all  germs  are  destroyed. 

STORAGE  OF    MISCELLANEOUS  GOODS. 

ARTICLES.  REMARKS. 

Canned  Goods:  °  F. 

Fruits 35 

Meats 35 

Sardines 35 

Flour  and  Meal: 

Buckwheat  flour 40 

Corn  meal 40 

Oat  meal 40 

Wheatflour 40 

Miscellaneous: 

Apple  and  peach  butter 40 

Chestnuts 33 

Cigars 35 

Furs,  woolens,  etc 25-32 

Furs,  undressed 35 

Game  to  freeze Long  storage  — 0-5 

Game,  after  frozen Short  storage 25-28 

Hops 33-36 

Honey 36-40 

Nuts  in  shell 35-38 

Maple  syrup,  sugar,  etc 40-45 

Oil 35 

Poultry,  after  frozen ....  Short  storage 28-30 

Poultry,  to  freeze Long  storage 5-10 

Syrup 35 

Tobacco 35 

LOWEST  COLD  STORAGE  TEMPERATURES. 

Temperatures  below  zero  Fahrenheit  are  hardly  of 
any  utility  in  cold  storage,  although  in  some  instances 
even  lower  temperatures  are  produced.  A  room  piped 
about  four  cubic  feet  of  space  to  one  lineal  foot  1-inch 
pipe,  direct  ammonia  expansion,  could  be  brought  to  8° 
F.  below  zero.  Theoretically  a  temperature  of  —28°  F. 
can  be  produced  with  ammonia  refrigeration  at  a  back 
pressure  equal  to  that  of  the  atmosphere  (and  even  lower 
at  lower  pressures),  but  practically  it  is  not  likely  that 
temperatures  lower  than  — 20°  F.  can  be  obtained  with 
ammonia,  although  it  may  be  done  by  carbonic  acid;  but 
as  stated  before,  it  is  to  no  purpose  as  far  as  cold  stor- 
age is  concerned. 


BREWERY   REFRIGERATION.  10" 

CHAPTER  VII.— BREWERY  REFRIGERATION. 

PRINCIPAL  OBJECTS  OF  BREWERY  REFRIGERATION. 

The  principal  uses  for  refrigeration  in  a  brewery  are 
as  follows: 

First. — Cooling  of  the  wort  from  the  temperature  of 
the  water  as  it  can  be  obtained  at  the  brewery  to  the 
temperature  of  the  fermenting  tuns  (about  40°  F. ). 

Second.— Withdrawal  of  the  heat  developed  by  the 
fermentation  of  the  wort. 

Third. — Keeping  cellars  and  store  rooms  at  a  uniform 
low  temperature  of  about  32°  to  38°  F. 

Fourth.—  Cooling  brine  or  water  to  supply  attemper- 
ators  in  fermenting  tubs. 

Fifth.— For  the  storage  of  hops  and  prospectively  in 
the  malting  process. 

ROUGH  ESTIMATE  OF  REFRIGERATION. 

Frequently  the  amount  of  refrigeration  required  for 
breweries  is  roughly  estimated  (in  tons)  by  dividing  the 
capacity  of  the  brewery  in  barrels  made  per  day  by  the 
figure  (4).  As  a  matter  of  course,  this  can  answer  only 
for  very  crude  estimates.  For  closer  estimates  the  dif- 
ferent purposes  for  which  refrigeration  is  required  must 
be  considered  separately. 

SPECIFIC  HEAT  OF  WORT. 

The  wort  by  the  fermentation  of  which  the  beer  is 
produced  consists  chiefly  of  saccharine  and  dextrinous 
matter  dissolved  in  water.  Its  specific  heat,  which  is 
the  chief  quality  that  concerns  us  now,  varies  with  the 


Strength  of  Wort  in 
Per  Cent  after 
Balling. 

Corresponding  Specific 
Gravity. 

Corresponding 
Specific  Heat. 

8 

1.0330 

.944 

9 

1.0363 

.937 

10 

1.0404 

.930 

11 

1.0446 

.923 

12 

.0488 

.916 

13 

.0530 

.909 

14 

.0572 

.902 

15 

.0614 

.895 

16 

.0657 

.888 

17 

.0700 

.881 

18 

.0744 

.874 

19 

.0788 

.867 

20 

1.0832 

.861 

amount  of  solid  matter  which  it  contains;  this  may  be 
ascertained  by  finding  its  specific  gravity  by  means  of  a 
odccharometer  or  other  hydrometer.  The  specific  heat 


MECHANICAL  REFRIGERATION. 

of  wort  of  different  strength  or  specific  gravity  may  be 
found  from  the  accompanying  table. 

These  figures  are  calculated  for  a  temperature  of  60° 
F.  For  every  degree  Fahrenheit  that  th£  temperature  of 
the  wort  is  below  60°,  the  number  0.00015  must  be  added 
to  the  specific  gravity  given  in  above  table,  and  for  every 
degree  above  the  number  0.00015  must  be  subtracted. 
Thus  the  specific  gravity  of  a  wort  of  13  per  cent  being 
acccording  to  the  table  1.0530  at  60°,  at  50°  it  would  be 
60  —  50=10x0.00015  =  0.0015  more,  or  1.0545. 

PROCESS  OF  COOLING  WORT. 

The  wort  as  prepared  in  the  brewery  is  boiling  hot, 
and  has  to  be  cooled  to  the  temperature  of  the  ferment- 
ing tuns.  It  is  first  cooled— at  least,  generally  so— by  ex- 
posing it  to  the  atmosphere  in  the  cooling  vat,  in  which, 
however,  it  should  not  remain  over  two  to  three  hours, 
nor  at  a  temperature  below  110°  F.  After  this  the  wort 
is  allowed  to  trickle  over  a  system  of  coils  through  which 
ordinary  cold  water  circulates  by  which  the  temperature 
of  the  wort  is  reduced  to  that  of  the  water,  about  60°  F. 
or  thereabouts.  A  system  of  coils,  generally  placed  be- 
low the  one  mentioned  already,  finishes  the  cooling 
process  by  reducing  the  temperature  of  the  wort  to  about 
40°  F.  or  below— in  ale  breweries  to  about  55°  F.  This  is 
done  by  circulating  either  cooled  (sweet)  water  or  refrig- 
erated brine  or  refrigerated  ammonia  through  the  latter 
coils  while  the  wort  trickles  over  the  same. 

REFRIGERATION  REQUIRED  FOR  COOLING  WORT. 

The  amount  of  cooling  required  in  this  latter  opera- 
tion must  be  furnished  by  artificial  refrigeration,  and  its 
amount  expressed  in  B.  T.  units,  U,  may  be  calculated 
exactly  if  we  know  the  number  of  barrels,  B,  of  wort  to 
be  cooled,  its  specific  heat,  s,  and  its  specific  gravity,  g, 
after  the  following  formula: 

TJ=*B  x  259  X  g  X  s  (t  —  40)  units, 

in  which  t  stands  for  the  temperature  to  which  the  wort 
can  be  cooled  by  the  water  to  be  had  at  the  brewery. 

To  reduce  this  amount  of  ^refrigeration  to  tons  of  re- 
frigeration it  must  be  divided  by  284,000. 

SIMPLE  RULE  FOR  CALCULATION. 

Assuming  that  the  average  temperature  of  the  wort 
after  it  has  been  cooled  b*7  the  water  as  it  is  obtainable 


BREWERY  REFRIGERATION.  199 

at  the  brewery,  is  about  70°  F.,  and  that  the  average 
strength  of  wort  in  breweries  is  between  13  and  15  per 
cent  of  extract,  corresponding  to  a  specific  weight  of 
about  1.05,  and  to  a  specidcheatof  0.9.  the  above  formula 
may  be  simplified  and  the  refrigeration  required  daily  for 
the  cooling  of  the  wort  of  a  brewery  j)f  a  daily  capacity 
of  B  barrels,  expressed  as  follows: 

U=Bx  7400  units. 
Or,  expressed  in  tons  of  refrigeration,  Ut 

' 


In  other  words,  about  one  ton  of  refrigeration  is  re- 
quired for  about  thirty-eight  barrels  of  wort  under  the 
conditions  mentioned.  If  the  water  of  tke  brewery  cools 
the  wort  to  60°,  one  ton  of  refrigeration  would  an- 
swer for  about  fifty-two  barrels  of  wort. 

The  former  figure  on  one  ton  of  refrigeration  for  forty 
barrels  of  wort  is  generally  adapted  for  preliminary  es- 
timates. 

SIZE  OF  MACHINE  FOR  WORT  COOLING. 

The  capacity  of  an  ice  machine  is  generally  expressed 
in  tons  of  refrigeration  produced  in  twenty-four  hours. 
However,  the  wort  in  a  brewery  must  be  cooled  in  a  few 
hours;  therefore,  in  order  to  find  the  capacity  of  the  ice 
machine  required  to  do  the  above  duty  the  number  of 
tons  of  refrigeration  found  to  be  required  to  do  the  cool- 

ing of  the  wort  must  be  multiplied  by  the  quotient  -V-  in 

fi 

which  h  means  the  time  expressed  in  hours  in  which  the 
cooling  of  the  wort  must  be  accomplished.  This  of 
course  applies  to  cases  in  which  a  separate  machine  is 
used  for  wort  cooling,  as  is  done  in  large  breweries. 

Frequently  the  cooling  of  the  wort  is  accomplished 
by  employing  nearly  the  whole  refrigerating  capacity  of 
the  brewery  for  this  purpose  for  a  comparatively  short 
time. 

INCREASED  EFFICIENCY  IN  WORT  COOLING. 

In  these  cases,  therefore,  the  total  refrigerating  ca- 
pacity of  a  brewery  must  never  be  less  than  that  required 
to  do  the  wort  cooling  in  the  desired  time  when  all  other 
refrigerating  activity  is  suspended  during  that  time.  In 
this  connection  it  should,  however,  be  mentioned  that 
the  brine  system,  as  well  as  the  direct  expansion  system, 


200  MECHANICAL    REFRIGERATION. 

may  be  made  to  work  with  increased  efficiency  when  ap- 
plied to  wort  cooling.  In  the  former  case  this  may  be 
accomplished  by  storing  up  cooled  brine  ahead,  and  in  the 
latter  case  by  allowing  the  ammonia  to  re-enter  the  com- 
pressor at  a  much  higher  temperature  after  having  been 
used  for  wort  cooling  than  in  other  cases. 

HEAT  PRODUCED  BY  FERMENTATION. 

The  cooled  wort  is  now  pitched  with  yeast  and  allowed 
to  ferment,  by  which  process  the  saccharine  constituents 
of  the  wort  are  decomposed  into  alcohol  and  carbonic  acid 
with  the  generation  of  heat  after  the  following  formula: 

C1Z  H22  0±1,  H2  0=4  Cz  HB  OH+  4  CO2  +  66,000  units. 
Maltose.  Alcohol.       Carbonic  Acid.       Heat. 

In  other  words,  this  means  that  360  pounds  of  malt- 
ose during  fermentation  will  generate  66,000  pounds  Cel- 
sius units  of  heat,  or  that  one  pound  of  maltose  while 
decomposed  by  fermentation  will  generate  about  330  B.T. 
units  of  heat. 

CALCULATING  HEAT  OF  FERMENTATION  IN  BREWERIES. 

If  the  weights  of  the  wort  and  that  of  the  ready  beer 
are  determined  by  means  of  a  Balling  saccharometer,  and 
are  b  and  bt  respectively,  the  heat,  H,  in  B.  T.  units  gen- 
erated during  the  fermentation  of  B  barrels  of  such  wort, 
may  be  determined  after  the  formula  — 

E==  B  X  0.91  (b-bj  (259+  6)  330  unita> 

100 

And  the  refrigeration  required  to  withdraw  this  heat 
from  the  fermenting  rooms,  expressed  in  tons,  U,  of 
refrigerating  capacity  is— 


SIMPLE  RULE  FOR  SAME  PURPOSE. 

Again,  if  we  assume  that  the  wort  on  an  average 
shows  14  per  cent  on  the  saccharometer,  and  after  fer- 
mentation it  shows  4  per  cent,  the  above  formula,  giving 
the  refrigeration  in  tons,  U^,  in  tons  required  in  twenty- 
four  hours  to  withdraw  the  heat  generated  by  the  fer- 
mentation of  B  barrels  of  wort  turned  in  on  an  average 
daily,  may  be  simplified  as  follows: 


fiREWERY    REFRIGERATION.  201 

In  other  words,  one  ton  of  refrigerating  capacity  is  re- 
quired for  every  thirty-four  barrels  of  beer  produced  on 
an  average  per  day  of  above  strength.  This  rule  will 
apply  to  pretty  strong  beers ;  for  weaker  beer  it  may  be- 
come much  less,  so  that  one  ton  of  refrigeration  will 
answer  for  fifty  barrels,  and  even  more.  This  shows 
the  importance  of  this  branch  of  the  calculation,  which 
is  frequently  passed  over  in  a  "  rule  of  thumb  "  way. 

For  preliminary  estimates  one  ton  of  net  refrigerat- 
ing capacity  is  allowed  to  neutralize  the  heat  generated 
by  the  fermentation  of  twenty-five  barrels  of  beer. 

DIFFERENT  SACCHAROMETERS. 

If  in  the  above  determinations  of  the  strength  of 
wort  of  beer  any  other  kind  of  saccharometer  has  been 
used  its  readings  can  be  readily  transformed  into  read- 
ings of  the  Balling  scale,  by  using  the  table  on  the  fol- 
lowing page,  which  may  also  be  used  in  connection  with 
the  other  tables  on  hydrometer  scales  in  this  book.  In 
this  way  any  hydrometer  may  be  made  available  for  the 
purpose  contemplated  in  the  above  formula. 

REFRIGERATION  FOR  STORAGE  ROOMS. 

Besides  the  heat  generated  by  fermentation,  the  heat 
entering  the  fermenting  and  storage  rooms  from  with- 
out must  be  carried  away  by  artificial  refrigeration,  so  as 
to  keep  them  at  a  uniform  temperature  of  32°  to  38P  F. 
The  amount  of  refrigeration  required  on  this  account  is 
also  frequently  estimated  by  a  "rule  of  thumb,"  allow- 
ing all  the  way  from  twenty  to  seventy  units  of  refrigera- 
tion for  every  cubic  foot  of  room  to  be  kept  cool  during 
twenty-four  hours.  The  difference  in  refrigeration  is  due 
to  the  size  of  the  buildings  and  to  the  manner  in  which 
the  walls  and  roofs  are  built. 

Generally  thirty  units  are  allowed  per  cubic  foot  of 
space,  in  rough  preliminary  estimates,  for  capacities  over 
100,000  cubic  feet. 

For  capacities  between  5,000  and  100,000  cubic  feet 
from  forty  to  seventy  units  are  allowed,  and  above  100,- 
000  from  twenty  to  forty  units  per  cubic  foot  of  space. 
Sometimes,  after  another  way  of  approximate  figuring, 
about  20  to  100  units  of  refrigeration  (generally  50)  are 
allowed  per  square  foot  of  surrounding  masonry  ceiling 
and  flooring. 


202 


MECHANICAL  REFRIGERATION. 


TABLES  FOB  THE  COMPARISON  OF  DIFFERENT  SACCHAR- 

OMETERS  AMONG  THEMSELVES  AND  WITH 

SPECIFIC  GRAVITY. 


•S  *•?  • 

1 

1 

£ 

•£ 

IT! 

L 

fe 

s' 

t" 

-. 

CO  4, 

—«*» 

S 

3! 

if 

•3| 

!! 

B 
o 

o 

ll 

ajl 

II 

il 
11 

J!  * 
O 

||| 

|s* 

CO 

Ow 

1 

|i 

js& 

1 

80 

Sf 

0.00 

0.00 

0.00 

1.000 

262.41 

12.00 

17.45 

14.fr 

1.0488 

275.21 

.25 

.36 

.30 

1.001 

262.66 

.25 

.83 

1.0498 

275.49 

..50 

.72 

,.60 

1.002 

262.92 

.50 

18.21 

15^2 

1.0509 

275.76 

.75 

1.08 

.90 

1.003 

263.18 

.76 

.60 

.60 

1.0520 

276.04 

1.00 

.44 

1.20 

1.004 

263.45 

13  00 

.99 

92 

1.0530 

276.32 

.25 

.80 

..60 

1.005 

263.71 

.25 

19.38 

16.24 

1  0540 

276.60 

,.50 

2  16 

.80 

1.006 

263.97 

.50 

.77 

.65 

1.0551 

276.88 

.76 

.62 

2.10 

1.007 

264.23 

.75 

20  16 

.86 

1.0662 

277.15 

2.00 

.88 

.40 

1.008 

264  50 

14.00 

.55 

17.17 

1  0572 

277.42 

.25 

3:24 

.70 

1.009 

264.76 

.25 

.94 

.48 

1.0582 

277.68 

.60 

.60 

3.00 

1.010 

265.02 

.50 

21.33 

.80 

1.0593 

277.96 

.75 

.96 

.30 

1.011 

265.28 

.75 

.72 

18.12 

1.0604 

278.25 

3.00 

4.32 

.60 

1.012 

265.55 

15.00 

22.11 

.43 

1.0614 

278.  52» 

.25 

.68 

.90 

1  013 

265.81 

.25 

.60 

.75 

1.0625 

278.80 

.60 

5.04 

4.20 

1.014 

266.07 

.50 

.89 

19  07 

1.0636 

279.09 

.75 

.40 

.50 

1.015 

266.33 

.75 

23.27 

.39 

1.0646 

279.86 

4.00 

.76 

.80 

1.016 

266.60 

16.00 

.66 

.71 

1.0657 

279.63 

.25 

6.12 

5.10 

1.017 

266.86 

.25 

24  05 

20.03 

1.0668 

279.92 

.50 

-.48 

.40 

1.018 

267.12 

.50 

.44 

.35 

1.0679 

280.21 

.75 

.84 

.70 

1.019 

267.38 

.75 

83 

.67 

1.0690 

280.60 

6.00 

7.20 

6.00 

1  020 

267.65 

17.00 

25.22 

21.00 

1.0700 

280.77 

.25 

.56 

.30 

1.021 

267  91 

.25 

.61 

.33 

1.07U 

281.06 

(.50 

.92 

.60 

1.022 

268  17 

.50 

26  00 

.66 

1.0722 

281.34 

.75 

8  28 

.90 

1*023 

268.43 

.75 

.39 

.99 

1.0733 

28163 

6.00 

.64 

7.20 

1*024 

268.69 

18.00 

.78 

22.32 

1-0744 

281.92 

.25 

9  00 

.50 

1J.025 

268.96 

.25 

27.17 

.65 

1.0755 

282.21 

.50 

.36 

80 

1?026 

269  2°. 

.50 

.56 

.98 

1.0766 

282.60 

.75 

-72 

8.10 

1.027 

269  48 

.75 

.96 

23.31 

1.0777 

282.78 

7.00 

10.08 

.40 

1  028 

269  74 

19  00 

28.36 

.64 

1.0788 

283.08 

.25 

.44 

.70 

1.029 

270.00 

.25 

.76 

•  97 

1.0799 

283  37 

.50 

.80 

9.00 

1  .030 

270.27 

.50 

29.16 

24.30 

1  0810 

283.65 

.75 

11.16 

.30 

1.031 

270.53 

.75 

.56 

.63 

1.0821 

283.93 

8.00 

.62 

.60 

1.032 

270.79 

20.00 

.95 

.96 

1.0832 

284.21 

.25 

.96 

.96 

1.0332 

271.11 

.25 

30.34 

25.29 

1.0843 

284  49 

.60 

12.32 

10.26 

1  0342 

271.37 

60 

.73 

.62 

1.0854 

284.77 

.75 

.68 

.57 

1  0352 

271  64 

.75 

31.12 

.95 

1.0865 

285.05 

9  00 

13  04 

.88 

1.0363 

271  91 

21.00 

.50 

26.27 

1  0876 

285.33 

.25 

.40 

11.19 

1  0374 

272.19 

25 

.87 

.60 

1.0887 

286  62 

.50 

.76 

.50 

1  0384 

272.47 

!50 

32  25 

93 

1.0898 

285.91 

.75 

14.12 

.81 

1.0394 

272.74 

75 

.64 

27.26 

1.0909 

286  19 

10.00 

.48 

12.11 

1.0404 

273.00 

22  00 

33.04 

.69 

1.0920 

286.47 

.25 

.84 

.42 

1.0415 

273.28 

.25 

.44 

.92 

1.0931 

286.77 

.50 

15.21 

.73 

1  0425 

273.56 

.50 

.84 

28.25 

1.0942 

287  06 

-75 

.58 

13  06 

1.0436 

273.84 

.75 

34.23 

.68 

1.0953 

287.36 

11.00 

.95 

.37 

1.0446 

274  11 

23.00 

.63 

.91 

1.0964 

287.66 

.26 

16.32 

.68 

1.0457 

274  39 

.25 

35.03 

29  24 

1  0976 

288.96 

.50 

.69 

14.00 

1.0467 

274  66 

.50 

.43 

.67 

1.0986 

288  20 

76 

17.07 

.32 

1.0478 

274.94 

.75 

83 

.90 

1.0997 

288.60 

24.00 

36.23 

30.23 

1.1008 

98880 

CLOSER  CALCULATION. 

For  calculations  required  to  be  more  exact  the  power 
for  transmission  of  heat  by  the  walls  and  windows,  as 
well  as  the  difference  of  temperature  within  and  without, 
must  be  taken  into  consideration. 


BREWERY    REFRIGERATION.  203 

For  calculations  of  this  kind  the  same  rules  apply 
which  have  been  given  under  the  head  of  cold  storage, 
pages  153,  etc. 

The  number  of  units  of  refrigeration  found  to  be 
required  must  be  divided  by  284,000  to  express  tons  of 
refrigeration. 

COOLING  BRINE  AND  SWEET  WATER. 

The  amount  of  refrigeration  required  to  cool  brine 
or  sweet  water  to  supply  the  attemperators  in  the  fer- 
menting tubs  is  included  in  the  estimate  for  the  refriger- 
ation required  to  neutralize  the  heat  of  fermentation. 

TOTAL  REFRIGERATION. 

Therefore  the  total  amount  of  refrigeration  required 
is  composed  of  the  first  three  items  mentioned  in  the 
second  paragraph  of  this  chapter,  and  by  adding  them 
we  find  the  actual  capacity  of  the  machine  or  machines 
required  in  a  given  case.  It  may  be  verified  in  accordance 
with  the  considerations  mentioned  in  the  paragraph  on 
"  Increased  Efficiency  for  Wort  Cooling." 

DISTRIBUTION  OF  REFRIGERATION. 

The  practical  distribution  of  the  refrigeration  in  the 
brewery  is  carried  out  on  different  principles,  and  should 
follow  the  figures  obtained  in  the  above  calculations. 

Formerly  the  cooling  of  rooms  in  breweries  was  fre- 
quently effected  by  the  circulation  of  air,  which  was 
furnished  direct  by  compressed  air  refrigerating  ma- 
chines. Later  on  the  air  to  be  used  for  this  purpose  was 
refrigerated  in  separate  chambers  with  the  aid  of  am- 
monia compression  machines.  At  present,  however,  the 
chief  means  for  cooling  brewery  premises  are  coils  of 
pipe  mto  which  the  ammonia  is  allowed  to  expand  di- 
rectiy  as  it  leaves  the  liquid  receiver.  These  coils  are 
generally  placed  overhead,  in  which  position  they  assist 
greatly  in  keeping  the  air  dry. 

DIMENSIONS  OF  WORT  COOLER. 

The  amount  of  refrigeration  destined  to  do  the  cool- 
ing of  the  wort  takes  care  of  itself,  provided  the  cooler, 
which,  as  already  described,  is  generally  constructed 
after  the  Baudelot  pattern,  is  large  enough  to  do  the 
cooling  in  the  proper  time.  The  proportions  frequently 
employed  for  the  ammonia  portion  of  the  wort  cooler  are 


204  MECHANICAL  REFRIGERATION. 

about  ter  lengths  of  2-inch  pipe,  each  length  sixteen 
feet  long,  for  fifty  barrels  of  wort  to  be  cooled  from  about 
70°  to  40°  F.  within  three  to  four  hours. 

For  100  barrels  of  wort  to  be  cooled  the  ammonia  por- 
tion of  the  cooler  consists  of  fourteen  lengths  of  pipe  six- 
teen feet  long;  for  180  barrels,of  fifteen  lengths  twenty  feet 
long;  and  for  360  barrels,  twenty  lengths  twenty  feet  long, 
all  pipes  to  be  2-inch.  These  are  practical  figures,  and 
given  with  a  view  to  afford  ample  cooling  surface. 

The  amount  of  refrigeration  which  must  circulate 
through  the  wort  cooler  within  that  time  has  been  deter- 
mined by  the  above  calculation. 

In  the  case  of  brine  circulation,  salt  brine  being  used 
in  the  wort  cooler,  the  surface  of  pipe  should  be  made  20 
percent  more  than  given  above;  in  other  words,  a  cooler 
of  the  above  dimensions  will  answer  for  forty  barrels  of 
wort,  instead  of  fifty,  in  case  brine  circulation  is  used. 

DIRECT  EXPANSION  WORT  COOLER. 

In  case  of  brine  circulation,  to  which  the  foregoing 
dimensions  apply,  the  pipes  of  the  wort  cooler  may  be  of 
copper,  but  in  case  of  direct  expansion  being  used,  the 
inside  of  the  pipes  cannot  be  copper,  but  must  be  iron  or 
steel,  and,  therefore,  copper  plated  steel  pipe  or  polished 
steel  pipe  is  used  in  this  case,  the  latter  being  given  the 
preference  by  most  manufacturers  on  account  of  cheap- 
ness and  relative  efficiency. 

The  ammonia  portion  of  the  wort  cooler  should  be 
made  in  two  or  more  sections,  having  separate  and  direct 
connections  for  inlet  of  liquid  ammonia  and  outlet  of  ex- 
panded vapor. 

PIPING  OF  ROOMS. 

The  balance  of  refrigeration,  that  is,  the  whole 
amount,  less  that  used  for  wort  cooling,  must  be  dis- 
tributed over  the  store  and  fermenting  rooms  in  due  pro- 
portion. In  doing  so  the  time  within  which  the  refrigera- 
tion is  to  be  dispensed  must  be  considered  foremost.  The 
subsequent  figures  are  based  on  the  assumption  that  dur- 
ing every  day  the  machine  or  brine  pump  is  active  for 
twenty-four  hours  to  circulate  refrigeration;  if  less  time 
is  to  be  used  for  that  purpose  more  distributing  pipe 
must  be  used  in  proportion. 

As  a  general  thing  too  much  piping  cannot  be  em- 
ployed, for  the  nearer  the  temperature  of  the  room  to  be 


cooled  is  to  that  within  the  pipe,  the  more  economical 
will  be  the  working  of  the  ice  machine. 

In  case  of  direct  expansion  it  is  frequently  assumed 
that  in  order  to  properly  distribute  one  ton  of  refrigera- 
tion about  storage  and  fermenting  rooms,  it  will  require 
a  pipe  surface  of  80  square  feet,  which  is  equivalent  to 
130  feet  of  2-inch  pipe,  and  to  about  190  feet  of  1^-inch 
pipe.  Smaller  pipe  than  that  it  is  not  advisable  to  use. 
If  radiating  disks  are  employed  less  pipe  may  be  used. 

For  brine  circulation  much  more  piping,  even  as 
much  as  200  square  feet  of  surface,  are  allowed  per  ton  of 
refrigeration  to  be  distributed. 

In  very  close  calculations  allowance  should  be  made 
for  the  difference  in  temperature  in  the  different  vaults, 
which  for  fermenting  rooms  is  about  42°  F.,  for  storage 
rooms  about  33-  F.,  and  for  final  storage  or  chip  cask 
about  37°  F. 

HEAT  OF  FERMENTATION  AGAIN. 

In  addition  to  the  piping  allowing  for  the  transmis- 
sion of  heat  through  the  walls,  the  balance  of  piping,  i.  e., 
that  which  is  to  convey  the  refrigeration  required  to 
neutralize  the  heat  during  fermentation,  must  be  appor- 
tioned according  to  the  amount  of  heat  which  is  de- 
veloped in  the  different  rooms.  This  can  also  be  calcu- 
lated very  closely  after  the  above  rules,  if  the  method 
of  fermentation  to  be  carried  on  is  known. 

But  as  a  rule  this  is  not  the  case,  and  to  supply  this 
deficiency  it  may  be  assumed  that  from  the  heat  gener- 
ated during  fermentation  about  four-fifths  is  generated 
in  the  fermenting  room,  and  about  one-fifth  in  the  ruh 
and  chip  cask  cellar  together.  In  this  proportion  the  ad- 
ditional piping  in  these  rooms  may  be  arranged  after  due 
allowance  has  been  made  for  the  refrigeration  conveyed 
by  the  attemperators. 

EMPIRICAL  RULE  FOR  PIPING  ROOMS. 

More  frequently  than  the  foregoing  method  empirical 
rules  are  followed  in  piping  rooms  in  breweries,  it  being 
assumed  that  nearly  all  of  the  heat  generated  in  the 
fermenting  room  proper  (during  primary  fermentation)  is 
carried  off  by  the  attemperators.  On  this  basis  it  is  fre- 
quently assumed  that  one  square  foot  of  pipe  surface  will 
cool  about  40  cubic  feet  of  space  in  fermenting  room,  and 
about  60  to  80  cubic  feet  of  space  in  ruh  and  chip  cask 
cellar  (direct  expansion). 


206  MECHANICAL    REFRIGERATION. 

These  figures  then  apply  to  direct  expansion; for  brine 
circulation,  about  one-half  of  the  above  named  spaces  will 
be  supplied  by  one  square  foot  of  refrigerating  surface. 

This  figure  appears  to  contemplate  a  range  of  about 
9°  F.  difference  between  the  temperature  of  rooms  and 
that  of  refrigerating  medium  within  pipe.  Much  more 
and  much  less  pipe  is  frequently  used  fcr  the  same  pur- 
pose, which  is  to  be  accounted  for  by  reasons  given  on 
pages  135  and  136. 

Here  we  allow  more  space  per  square  foot  of  refriger- 
ating pipe  surface  than  is  done  in  the  rule  at  the  bottom 
of  page  135  for  storage  rooms  in  general  to  keep  the  same 
temperature.  This  is  partially  explained  by  the  fact 
that  brewery  vaults  are  less  frequently  entered  from 
without,  and  that  their  contents  are  less  frequently 
changed  than  is  the  case  with  general  storage  vaults. 
Furthermore  it  is  evident  that  the  size  of  vaults  is  also  a 
matter  for  consideration  in  this  respect. 

ATTEMPERATORS. 

The  attemperators  are  coils  of  iron  pipe,  one  to  two 
inches  thick,  the  coil  having  a  diameter  of  about  two- 
thirds  of  the  diameter  of  the  fermenting  tub,  in  which  it 
is  suspended,  and  a  sufficient  number  of  turns  to  allow 
about  twelve  square  feet  pipe  surface  per  100  barrels  of 
wort,  corresponding  to  about  nineteen  feet  of  2-inch 
pipe.  The  refrigeration  is  produced  by  means  of  cooled 
water  or  brine  circulating  through  the  attemperators. 
The  attemperators  are  suspended  with  swivel  joints  so 
that  they  can  be  readily  removed  from  the  fermenting  tub. 

There  is  a  great  variety  in  the  form  of  attemperators, 
box  or  pocket  coolers  being  also  frequently  used.  On  the 
whole  the  pipe  attemperator  as  described  seems  to  be 
the  simplest  and  most  popular. 

It  has  also  been  proposed  (Galland)  to  cool  the  fer- 
menting wort  by  the  injection  of  air,  purified  by  filtration 
through  cotton  and  refrigerated  artificially.  This  plan, 
however,  does  not  seem  to  be  followed  practically  to  any 
great  extent. 

REFRIGERATION  FOR  ALE  BREWERIES. 

While  the  general  calculations  relating  to  heat  of 
fermentation,  cooling  of  the  wort  and  cooling  of  rooms 
are  the  same  for  ale  as  for  lager  beer,  the  specific  data 
relating  to  piping,  etc.,  in  above  paragraph,  are  given 


BREWERY  REFRIGERATION.  207 

with  special  reference  to  lager  beer,  and  must  be  modified 
when  applied  to  ale. 

This  is  due  to  the  fact  that  the  ale  wort  is  cooled  to 
a  temperature  of  about  55°  F.  only,  and  that  the  storage 
rooms  are  to  be  kept  at  a  temperature  of  50°  F.,  or  there- 
abouts. 

Accordingly,  for  ale  wort  cooling  one  ton  of  refriger- 
ation will  be  required  for  every  seventy-five  barrels.  For 
keeping  the  rooms  at  the  temperature  of  60°  about 
twenty  B.  T.  units  and  less  of  refrigeration  for  every 
cubic  foot  in  twenty-four  hours  will  be  sufficient. 

The  refrigeration  necessary  to  remove  the  heat  of 
fermentation  is  calculated  in  the  same  manner  as 
above. 

The  piping  of  store  rooms  in  ale  breweries  is  fre- 
quently done  at  the  rate  of  one  running  foot  of  2-inch  pipe 
per  sixty  cubic  feet  of  space. 

The  tables  on  refrigeration  and  piping  discussed  in 
the  chapter  on  cold  storage  may  also  be  consulted  in  this 
connection. 

SWEET  WATER  FOR  ATTEMPERATORS. 

The  circulation  of  refrigerated  brine  in  the  attem- 
perators  is  not  considered  a  safe  practice  by  brewers  in 
general,  as  a  possible  leak  of  brine  would  be  liable  to 
cause  great  damage  to  the  beer.  For  this  reason  cooled 
or  ice  water  (it  is  also  termed  sweet  water  to  distinguish 
it  from  salt  water  or  brine)  is  circulated  in  the  attem- 
perators,  generally  by  means  of  an  automatic  pump 
which  regulates  the  proper  supply  of  sweet  water  to  the 
attemperators,  no  matter  how  many  or  how  few  of  them 
are  in  operation  at  the  time.  The  ice  or  sweet  water  is 
cooled  in  a  suitable  cistern  or  tank  which  contains  a 
cooling  pipe  in  which  ammonia  is  allowed  to  expand  di- 
rectly, or  through  which  refrigerated  brine  is  allowed  to 
circulate.  In  some  breweries  the  wort  is  also  cooled  by 
refrigerated  sweet  water  made  in  the  above  way.  This 
method  absolutely  precludes  the  possibility  of  contami- 
nation of  ammonia  or  brine,  but  at  the  same  time  it  is 
very  wasteful  in  regard  to  the  very  indirect  mode  of  ap- 
plying the  refrigeration*,  and  for  this  reason  brine  in  cir- 
culation is  now  mostly  used  for  this  purpose,  experience 
having  shown  that  the  danger  of  contamination  is  prac- 
tically excluded. 


208  MECHANICAL  REFRIGERATION. 

CHILLING  OF  BEER. 

Recently  it  has  been  found  desirable  to  subject  the 
ready  beer  to  a  sort  of  chilling  process  immediately 
before  racking  it  off  into  shipping  packages.  This  pro- 
cess, however,  is  of  no  practical  utility  if  the  beer  is  not 
filtered  after  it  has  been  chilled  and  before  it  goes  into 
the  barrels.  In  this  case  much  objectionable  albuminous 
matter,  still  contained  in  the  ready  beer,  is  precipitated 
by  chilling  and  separated  from  the  beer  by  filtration, 
while  without  filtration-  this  matter  would  redissolve 
in  the  beer  and  cause  subsequent  turbidities,  especially 
if  the  beer  is  used  for  bottled  goods. 

BEER  CHILLING  DEVICES. 

The  chilling  was  first  effected  by  passing  the  beer 
through  a  copper  worm  placed  in  a  wooden  tub  which 
was  filled  with  ice.  But  by  this  the  desired  object  was 
attained  only  partially.  Therefore,  the  ice  was  mixed 
with  salt  to  obtain  a  still  lower  temperature  in  the  beer 
passing  through  the  worm.  Still  more  recently,  and  of 
course  in  all  breweries  where  mechanical  refrigeration  is 
employed,  the  pipes  through  which  the  beer  passes  are 
cooled  by  brine  or  by  direct  expansion. 

Special  apparatus  are  also  made  for  this  purpose,  and 
generally  consist  of  a  series  of  straight  pipes  provided 
with  manifold  inlet  and  outlet,  and  placed  in  a  cylindrical 
drum,  through  which  refrigerated  brine  or  ammonia  is 
allowed  to  pass  in  a  direction  opposite  to  the  beer. 

COOLING  OF  WORT. 

Coolers  of  the  same  construction  are  now  also  fre- 
quently used  for  wort  cooling  instead  of  the  Baudelot 
coolers.  For  both  purposes,  i.  e.,  the  chilling  of  the  ready 
beer  and  the  cooling  of  the  wort,  the  refrigerated  brine 
appears  to  act  as  the  best  cooling  medium,  at  least  so  with 
some  makes  of  this  kind  of  coolers  as  they  are  constructed 
and  operated  at  present.  If  direct  expansion  is  used  it  has 
been  found  impracticable  (at  least  in  the  cases  reported 
to  the  author)  to  effect  a  thorough  chilling  in  the  desired 
time.  If  used  for  wort  cooling,  direct  expansion  has 
also  caused  some  trouble  when  used  witli  some  kinds  of 
these  new  coolers,  but  it  has  been  overcome  in  a  measure 
by  allowing  the  ammonia  to  enter  the  cooler  almost  on«»- 
half  to  one  hour  before  the  wort  is  passed  through  the 
same. 


BREWERY  REFRIGERATION.  209 

SAFEGUARDS    TO  BE   EMPLOYED. 

It  has  also  been  experienced  that  the  expanded 
ammonia,  especially  if  the  expansion  valve  (one  of  which 
must  be  provided  for  each  of  these  coolers)  is  not  mani- 
pulated very  carefully,  enters  the  compressor  in  an  over- 
saturated  condition  if  allowed  to  pass  directly  to  the 
same.  Under  such  conditions  the  compressor  will  oper- 
ate in  an  irregular  manner,  and  even  the  cylinder  head 
may  be  blown  out  in  extreme  cases.  To  guard  against 
such  calamities  it  is  necessary  to  carry  the  expanded 
ammonia  to  the  compressor  in  proper  condition  by  allow- 
ing the  same  to  mix  with  the  expanded  ammonia  coming 
from  the  expansion  pipes  in  other  parts  of  the  brewery, 
before  reaching  the  compressor.  To  do  this  the  ex- 
panded ammonia  from  the  wort  cooler  and  that  from  the 
cellar  may  enter  a  common  conduit  pipe  at  a  sufficient 
distance  from  the  compressor  to  insure  a  thorough  mix- 
ture of  the  gases. 

CAUSES    OF    TROUBLE. 

The  foregoing  contains,  we  believe,  the  principal 
safeguards  known  at  present  to  be  of  service  to  over- 
come the  troubles  with  these  coolers;  troubles  which, 
while  they  are  not  gainsaid  by  their  makers,  are  never- 
theless, we  understand,  declared  by  some  of  them  so 
paradoxical  in  their  action  that  they  upset  the  entire 
theory  of  transmission  of  heat  as  given  by  the  scientists 
at  present.  On  the  other  hand,  and  to  partly  offset  a 
statement  so  derogatory  to  the  engineering  profession, 
it  may  be  permissible  to  suggest  that  the  chief  of  the 
apparatus  makers,  while  being  expert  practical  copper- 
smiths, are  perhaps  not  sufficiently  versed  in  the  intricate 
details  offered  by  problems  of  heat  transmission  to  give 
the  construction  of  apparatus  of  a  novel  tendency  the 
proper  consideration. 

It  is  not  unlikely  that  the  relative  sizes  of  direct 
expansion  pipes  and  brine  pipes  in  the  refrigeration  of 
rooms  have  been  taken  as  cases  parallel  to  these  coolers, 
while  in  fact  the  transmission  of  heat  proceeds  at  a 
rate  entirely  different  in  both  cases. 

DIRECT  REFRIGERATION. 

Instead  of  refrigerating  the  fermenting  and  storage 
rooms  of  the  brewery  it  has  also  been  proposed  to  refrig- 
erate the  contents  of  the  tubs  and  casks  separately  and 
in  a  more  direct  manner,  just  as  the  surplus  heat  of  fer- 


210  MECHANICAL  REFRIGERATION. 

meriting  tubs  is  now  withdrawn,  by  means  of  attempera- 
tors  or  similar  devices.  At  first  sight  there  would  seem 
to  be  a  source  of  considerable  saving  in  this  proposition, 
but  it  would  be  at  the  expense  of  cleanliness,  dryness  and 
reliable  supervision  of  the  brewery.  Therefore  it  must 
be  considered  a  change  of  very  doubtful  expediency. 

BREWERY  SITE. 

In  former  times  it  was  generally  considered  that  the 
best  location  for  a  brewery  site  was  on  a  hill  side,  to 
enable  the  fermenting  and  storage  rooms  to  be  built  into 
the  hill  into  natural  rock,  in  order  to  profit  by  the 
natural  low  underground  temperature  in  the  summer 
and  the  higher  underground  temperature  in  the  winter 
time;  in  other  words,  by  the  even  temperature  all  the 
year  around.  This  position  was  certainly  well  taken 
when  the  beer  was  made  exclusively  by  top  fermenta- 
tion, and  the  position  still  holds  good  in  a  measure  for 
ale  breweries.  As  the  great  majority  of  breweries,  how- 
ever, are  operated  for  the  production  of  lager  beers 
which  have  to  ferment,  and  are  stored  at  temperatures 
much  lower  than  those  obtaining  in  natural  vaults  (at 
least,  in  the  moderate  zones),  artificial  refrigeration  or  ice 
has  to  be  resorted  to.  In  either  case  the  natural  vaults 
offer  very  little  advantage  to  overground  structures,  well 
insulated,  especially  if  the  larger  cost  of  construction 
of  natural  vaults,  their  inconvenience  as  to  room,  and 
generally  also  as  to  accessibility, is  considered.  For  these 
reasons  the  site  for  a  brewery  nowadays  is  generally 
selected  with  sole  reference  to  convenience  as  to  ship- 
ment of  produce,  reception  of  material  and  quality  and 
accessibility  of  water  supply. 

ICE  MAKING  AND  BREWERY  REFRIGERATION. 

Very  frequently  it  happens  that  a  brewery  is  to  be 
operated  in  connection  with  an  ice  plant,  and,  generally 
speaking,  it  is  doubtless  not  only  more  convenient,  but 
also  good  economy  to  have  more  than  one  refrigerating 
machine  in  such  cases  on  account  of  different  expansion 
or  back  pressures  that  we  have  to  work  with. 

STORAGE  OF  HOPS. 

To  keep  hops  from  degeneration  their  storage  at  32° 
—34°  F,  in  a  dry,  dark,  insulated  room  has  been  found 
the  only  successful  way.  The  hops  should  be  well  dried, 
sulphurized  and  well  packed  before  being  placed  in  cold 
storage.  Artificial  refrigeration,  as  well  as  ice,  may  be 


BREWERY  REFRIGERATION.  211 

used,  but  special  precaution  has  to  be  used  to  keep  the 
room  dry  in  the  latter  case. 

REFRIGERATION  IN  MALT  HOUSES 

The  cold  air  which  is  required  in  malting,  especially 
in  the  so  called  pneumatic  methods  of  malting,  it  has 
also  been  proposed  to  furnish  by  means  of  refrigerating 
machinery,  but  it  does  not  appear  that  it  can  be  done 
successfully  from  a  financial  point  of  view,  except, 
perhaps,  under  very  exceptional  circumstances. 

ACTUAL  INSTALLATIONS. 

The  following  figures  are  taken  from  actual  meas- 
urements of  an  existing  installation  in  a  brewery  having 
a  daily  capacity  of  375  barrels  lager  beer,  which  has  the 
following  appointments : 

One  ammonia  compression  machine  of  fifty  tons, 
chiefly  for  wort  'cooling,  direct  expansion,  reduces  tem- 
perature of  whole  output,  375  barrels,  from  70°  to  40°  F. 
in  four  hours  (the  ammonia  portion  of  Baudelot  cooler 
consisting  of  twenty  pieces  of  2-inch  pipe,  each  twenty 
feet  long). 

One  ammonia  compression  machine,  50  tons  capacity, 
for  storage .  attemperators,  etc.  (direct  expansion). 

Fermenting  room,  90x75  feet,  fourteen  feet  high,  is 
piped  at  the  rate  of  one  foot  2-inch  pipe  for  every 
twenty- seven  cubic  feet  space.  Each  one  of  the  sixty- 
five  fermenting  tubs  contains  an  attemperator  coil  of 
twenty-one  feet  2-inch  pipe. 

Ruh  cellar,  90X74  feet,  and  twenty  feet  high,  is  piped 
at  the  rate  of  one  foot  2-inch  pipe  for  every  forty  cubic 
feet  of  space. 

Chip  cask  cellar,  90x73  feet,  and  sixteen  feet  high,  is 
piped  at  the  rate  of  one  foot  2-inch  pipe  for  every  fifty- 
two  cubic  feet  of  space. 

A  fifty-barrel  lager  beer  brewery  was  equipped  with 
machinery  to  furnish  refrigeration  in  accordance  with 
the  following  estimates : 

3,200,000  B.  T.  units  for  storage. 
416,000  B.  T.  units  for  cooling  wort. 
300,000  B.  T.  units  for  attemperators. 

Total,  3,916,000  B.-T.  units=13.8  tons,  or  in  round  figures 
equal  to  fifteen  tons  refrigerating  capacity.  The  whole 
capacity  is  calculated  to  cool  the  wort  in  four  hours. 


212  MECHANICAL  REFRIGERATION. 

CHAPTER  VIII.— REFRIGERATION  FOR 
PACKING  HOUSES,  ETC. 

AMOUNT  OF  REFRIGERATION  REQUIRED. 

The  application  of  refrigeration  in  slaughtering  and 
packing  houses  is  quite  similar  to  its  application  to  cold 
storage  in  general,  and  the  amount  of  refrigeration  re- 
quired in  a  -special  case  may  be  estimated  on  the  same 
principles. 

THEORETICAL  CALCULATION  OF  SAME. 

The  refrigeration  required  to  keep  the  rooms  at  the 
required  temperature  is  found  after  the  rules  given  on 
page  151,  etc.  The  additional  refrigeration  to  chill  or 
freeze  the  meat  can  be  calculated  after  the  rules  given 
on  page  157,  etc. 

PRACTICAL  RULES  FOR  SAME. 

The  temperature  of  the  chilling  rooms  is  below  32°  F. 
and  the  fresh  slaughtered  meats  are  stored  in  them  until 
they  have  acquired  the  storage  temperature  in  storage 
rooms,  to  which  they  are  then  removed. 

For  practical  estimates  it  is  frequently  assumed  that 
a  refrigeration  equivalent  to  about  80  B.  T.  units  is  re- 
quired for  every  cubic  foot  of  chilling  room  capacity  in 
twenty-four  hours. 

The  refrigeration  for  meat  storage  rooms  is  the  same 
as  that  required  for  ordinary  storage,  i.  e. ,  from  20  to  50 
units  (40  units  being  calculated  on  an  average)  for  every 
cubic  foot  of  space  in  twenty-four  hours. 

For  crude  estimates  calculations  are  frequently  made 
on  the  basis  of  allowing  3,000  to  5,000  cubic  feet  space 
per  ton  of  refrigeration  in  twenty-four  hours  in  chilling 
rooms,  and  5,000  to  8,000  cubic  feet  space  per  ton  of  refrig- 
eration in  twenty-four  hours  in  storage  rooms,  accord- 
ing to  insulation,  size  of  rooms  and  other  conditions. 

FREEZING  ROOMS. 

The  freezing  of  meat  is  performed  in  rooms  kept  at  a 
temperature  of  10°  F.  and  below.  Considerable  additional 
refrigeration  is  required  for  freezing,  not  only  on  account 
of  the  latent  heat  of  freezing,  which  has  to  be  withdrawn, 
but  also  on  account  of  the  low  temperature  at  which  the 
rooms  have  to  be  kept.  For  rough  estimates  at  least  200 


REFRIGERATION  FOR  PACKING   HOUSES  213 

B.  T.  units  of  refrigeration  should  be  allowed  for  every 
cubic  foot  of  freezing  room  capacity. 

CALCULATION  PER   NUMBER  OF  ANIMALS. 

If  the  average  number  and  kind  of  animals  to  be  dis- 
posed of  daily  in  slaughtering  house  is  known,  calcula- 
tions are  also  made  on  a  basis  similar  to  the  following: 

From  6,000  to  12,000  cubic  feet  of  space  are  allowed  per 
ton  of  refrigerating  capacity  to  offset  the  loss  of  refrig- 
eration by  radiation  through  walls  and  otherwise,  and  in 
addition  to  that,  the  extra  refrigeration  to  be  allowed  in 
the  chilling  room  for  the  chilling  proper  is  arrived  at  in 
accordance  with  the  assumption  that  one  ton  of  refriger- 
ation will  take  care  of  the  chilling  of 

15-24  hogs     (average  weight,  250  pounds). 
5-  7  beeves  (average  weight,  700  pounds). 
45-55  calves  (average  weight,  90  pounds). 
55-70  sheep  (average  weight,  75  pounds). 
In  actual  freezing  one  ton  of  refrigeration  will  take 
care  of  one  ton  of  meat  (in  twenty-four  hours). 

PIPING  OF  ROOMS. 

The  piping  of  rooms  in  packing  houses  may  be  ar- 
ranged after  rules  referred  to  already.  Not  infrequently, 
however,  other  empirical  rules  are  followed,  viz.: 

For  chilling  rooms,  for  instance,  one  running  foot  of 
2-inch  pipe  (or  its  equivalent)  is  allowed  for  thirteen  to 
fourteen  cubic  feet  of  space ;  that  is,  in  case  of  direct 
expansion,  and  for  seven  to  eight  cubic  feet  of  space 
for  brine  circulation. 

For  storage  rooms,  one  running  foot  of  2-inch  pipe 
is  allowed  for  forty-five  to  fifty  cubic  feet  in  case  of  di- 
rect expansion,  and  for  fifteen  to  eighteen  cubic  feet 
in  case  of  brine  circulation. 

For  freezing:  rooms,  one  running  foot  of  2-inch  pipe 
is  allowed  for  six  to  ten  cubic  feet  of  space  for  direct 
expansion,  and  for  three  cubic  feet  of  space  in  case  of 
brine  circulation. 

Others  proportion  the  piping  by  the  number  of  ani- 
mals slaughtered,  allowing  thirteen  feet  of  2-inch  pipe 
per  ox,  and  six  feet  2-inch  pipe  per  hog  in  case  of  direct 
expansion  in  chilling  room. 

In  case  of  brine  expansion  thirteen  feet  1^-inch  pipe 
are  allowed  per  hog,  and  twenty-seven  feet  1^-iuch  are  al- 
lowed per  ox  in  chilling  room.  (Large  installations.) 


214  MECHANICAL   REFRIGERATION, 

STORAGE  TEMPERATURES  FOB-  MEATS. 

The  temperatures  considered  best  adapted  for  the 
storage  of  various  kinds  of  meats  are  given  in  the  follow- 
ing table: 

ARTICLES.  °  F. 

Brined  meats 35-40 

Beef,  fresh 37-39 

Beef,  dried 36-45 

Hams,  ribs,  shoulders  (not  brined) 30-35 

Hogs 30-33 

Lard , 34-45 

Livers.-. 30 

Mutton  32-36 

Oxtails 32 

Sausage  casings 30-35 

Tenderloins,  butts,  ribs 30-35 

Veal 32-36 

OFFICIAL  VIEWS  ON  MEAT  STORAGE. 

The  report  of  an  official  commission  created  by  the 
French  government  to  investigate  the  cold  storage  of 
meats,  etc  ,  closes  with  the  following  conclusions : 

First. — Whenever  meat  is  to  be  preserved  for  a  com- 
paratively short  time,  for  market  purposes,  the  animals 
being  slaughtered  close  to  the  cold  storage  or  not  having 
to  be  transported,  after  slaughtering,  for  a  distance  in- 
volving more  than  a  few  hours  (as  much  as  twelve),  in 
transit,  congelation  is  not  required  to  insure  the  con- 
servation. It  should  be  avoided,  as  by  such  a  practice, 
that  is,  the  temperature  being  kept  in  the  storage  above 
the  freezing  point,  the  meats  are  sure  to  retain  all  'jheir 
palatable  and  merchantable  qualities. 

Second. — In  special  circumstances,  such  as  for  a  pro- 
tracted conservation,  in  case  of  a  transportation  of  the 
slaughtered  animals  from  very  long  distances,  involving 
days  or  weeks  in  transit,  congelation  appears  to  be  pref- 
erable and  safer  It  does  not  necessarily  render  the 
meats  less  merchantable,  wholesome  or  palatable,  if  they 
are  frozen  and  thawed  out,  very  slowly,  gradually  and 
carefully;  and  only  after  they  have  been  deprived  partially 
of  the  excess  of  moisture  of  their  tissues. 

Third.—  Cold,  dry  air  should  be  the  vehicle  of  cold;  it 
should  circulate  freely  around  the  meats. 

FREEZING  MEAT. 

The  same  commission  recommends  that  in  case  the 
meat  must  be  frozen  it  should  be  done  in  such  a  way  that 
the  fiber  is  not  altered;  it  should  preserve  its  elasticity 
as  long  as  possible,  up  to  the  very  moment  when  the  liquid 
elements  of  the  meat  begin  to  solidify,  so  that,  at  the 


REFRIGERATION  FOR  PACKING  HOUSES.  215 

point  of  congelation,  the  dilatation  of  the  water,  in 
changing  state,  should  not  cause  the  bursting  of  the  or- 
ganic cells,  leaving  a  uniform  mass  of  disagreeable  ap- 
pearance at  the  thawing  out.  The  congelation  must 
proceed  very  slowly  from  the  start,  progressing  gradually 
and  very  regularly  through  the  mass,  as  soon  as  the 
freezing  point  has  been  reached;  the  temperature  should 
be  carefully  watched,  very  evenly  lowered  without  any 
sudden  depression.  Once  congealed,  the  temperature  of 
the  meats  can  be  carried  very  low  without  detriment. 

CIRCULATION  OF  AIR  IN  MEAT  ROOMS. 

The  required  circulation  of  air  in  the  meat  rooms  is 
either  produced  by  natural  draft  or  (especially  in  Europe) 
by  means  of  blowers  or  fans,  which  circulate  air, 
cooled  artificially.  The  cooling  of  air  used  for  the  latter 
purpose  is  generally  done  in  a  separate  room  in  which 
the  air  is  brought  in  contact  with  the  surfaces  of  pipes 
which  are  refrigerated  by  direct  ammonia  expansion. 
The  warmer  air  is  continuously  exhausted  from  the  meat 
rooms  by  means  of  a  blower,  which  forces  it  through  the 
cooling  apparatus  and  thence  back  to  the  meat  rooms  in 
a  cold  and  dry  condition. 

See  also  what  has  been  said  on  ventilation,  etc.,  in 
the  chapter  on  cold  storage. 

BONE  STINK. 

As  already  stated,  the  freezing  of  meat  must  be  done 
very  carefully,  in  order  to  avoid  any  injury  to  the  meat. 
Moro  particularly  the  chilling  and  freezing  must  be  done 
very  gradually,  for  when  the  meat  is  plunged  at  once  in 
a  chamber  below  the  freezing  point,  the  external  parts 
are  frozen  more  quickly  than  the  internal  parts,  and  the 
latter  are  cut  off  by  this  external  frozen  and  poorly  con- 
ducting zone  from  receiving  the  same  intensity  of  cold. 
The  external  frozen  zone  contracting  on  the  internal 
portion  causes  many  of  the  cells  to  be  ruptured  and  the 
contents  to  escape,  and  on  cutting  into  meat  so  frozen  a 
pulpy  consistency  of  the  meat  is  found  near  the  bones. 
This  is  particularly  the  case  when  whole  carcasses  are 
treated,  but  also  parts  of  the  animal  show  similar 
defects  when  frozen  carelessly.  The  so  called  "bone 
stink,"  which  shows  itself  as  decaying  marrow  in  the 
interior  of  the  bones  of  many  frozen  meats,  is  also  gen- 
erally due  to  the  too  hasty  freezing.  However,  the  con- 
dition of  animal  at  the  time  of  killing  (exhaustion  by  a 


216  MECHANICAL  REFRIGERATION. 

long  journey,  injudicious  feeding,  excitement,  delay  in 
skinning,  etc.)  appears  to  favor  the  liability  to  bone 
stink. 

Hanging  the  animals  too  closely  together  after  they 
are  slaughtered  and  dressed  is  said  to  be  a  fruitful  source 
of  bone  taint,  for  when  they  are  throwing  off  the  animal 
heat  and  gases  contained  in  the  bodies,  if  hung  too 
closely  together  they  will  steam  one  another  and  prevent 
this  animal  heat  and  gas  from  getting  away.  The  ab- 
sence of  proper  ventilation  and  an  insufficient  circulation 
of  fresh  air  is  also  a  likely  cause,  bearing  in  mind  that 
what  has  to  be  aimed  at  is  the  driving  away  of  this  ani- 
mal heat  and  gas  as  it  passes  out  of  the  carcass.  While 
the  temperature  of  the  cooling  chamber  should  be  kept 
moderately  low,  it  should  not  be  too  low;  a  free  circula- 
tion being  of  far  more  importance  than  lowness  of  tem- 
perature during  this  early  cooling  or  chilling  process. 

Bone  taint  can  be  detected  without  actually  cutting 
up  a  carcass,  in  the  following  way:  A  long  wooden 
skewer  is  inserted  at  the  point  of  the  aitch  bone;  this 
passes  the  cup  bone  and  enters  the  veins  that  divide  the 
silver  side  from  the  top  side,  where,  if  any  taint  exists, 
it  is  sure  to  be  found,  the  wooden  skewer  bringing  out 
the  taint  upon  it.  For  testing  while  in  a  frozen  state  a 
carpenter's  brace  and  bit  should  be  used.  This  must  be 
inserted  as  above  described. 

FREEZING  MEAT  FROM  WITHIN. 

It  has  also  been  proposed  to  prevent  the  bone  stink, 
etc.,  by  freezing  meat  from  the  center  by  introducing 
into  the  same  a  pipe  shaped  like  a  hollow  sword  divided 
by  a  partition  around  which  refrigerated  brine  or  am- 
monia is  permitted  to  circulate. 

DEFROSTING  OF  MEAT. 

The  importance  of  doing  the  defrosting  of  meat  with 
the  same  care  as  the  freezing  is  well  illustrated  by  a 
number  of  patents  taken  out  for  this  operation.  One  of 
these  processes  subjects  the  meat  to  a  continuous  circu- 
lation of  dry  air  formed  by  mixing  cold  air  at  a  tempera- 
ture of  19°  and  dry  air  heated  to  70°,  the  combined  cur- 
rent at  about  26°,  increased  to  about  60°,  being  forced 
through  the  thawing  chamber  by  a  fan.  Time  required 
for  thawing,  two  to  five  days.  This  process  is  in  use  at 
Malta  and  Port  Said. 

Another  patent  provides  for  the  circulation  ol  air, 


REFRIGERATION  FOR   TACKING   HOUSES.  217 

dried  by  arrangement  of  pipes  containing  cooling  me- 
dium, and  suitably  heated  by  steam  pipes,  passing  over 
the  meat  by  natural  means,  and,  by  gradually  increasing 
temperature,  abstracting  the  frost  without  depositing 
moisture.  Time  required  for  defrosting:  Beef,  four  days; 
sheep,  two  days.  Process  has  been  in  continuous  use  in 
London  for  two  and  one-half  years;  it  is  also  used  in 
Paris  and  in  Malta  for  meat  supplied  to  troops. 

MOLDY  SPOTS  ON  MEAT. 

The  white  mold  spots  which  sometimes  form  on  meat 
in  cold  storage  are  due  to  the  growth  of  a  fungus  (Oidium 
albicans)  the  germs  of  which  are  quite  common  in  the 
air.  For  this  reason  the  formation  of  this  mold  may  be 
prevented  by  providing  a  circulation  of  air  which  has 
passed  over  the  cooling  pipes  (St.  Clair's  system,  described 
under  "Cold  Storage") ,  by  which  the  moisture  and  mold 
germs  are  withdrawn  from  the  air. 

KEEPING  OF  MEAT. 

Meat,  if  kept  constantly  at  31°  in  a  properly  venti- 
lated room  from  the  time  it  has  been  slaughtered  can  be 
kept  fresh  at  least  six  months,  '~>ut  if  the  temperature 
goes  up  at  times  as  high  as  even  only  33°  the  meat  might 
not  keep  over  a  month;  however,  if  the  ventilation  and 
humidity  are  properly  regulated  it  should  keep  about  two 
months  in  good  condition  in  the  latter  case. 

Beef  should  be  placed  in  cold  storage  within  ten 
hours  after  killing. 

SHIPPING  MEAT. 

Meat  properly  prepared  may  be  kept  at  a  tempera- 
ture between  32°  and  35°  F.  for  any  length  of  time,  but 
to  insure  against  a  break  down  of  the  refrigerating  ma- 
chinery aboard  the  vessel,  the  meat  is  generally  frozen  be- 
fore it  is  loaded,  thus  providing. for  a  deposit  of  cold  (100 
tons  of  frozen  meat  being  equivalent  for  refrigerating 
purposes  to  seventy  tons  of  ice)  that  can  be  drawn  on  in 
case  the  machinery  fails  temporarily. 

REFRIGERATION    FOR  OTHER   PURPOSES. 

From  the  data,  rules  and  examples  given  under  the 
heads  of  cold  storage,  packing  house  and  brewery  re- 
frigeration, and  on  refrigeration  in  general,  it  will  be 
practicable  to  make  the  required  approximate  estimates 
for  most  of  the  other  numerous  applications  of  refrig- 
erating machinery. 


218  MECHANICAL  REFRIGERATION. 

REFRIGERATION  IN  OIL  WORKS. 

In  oil  refineries  artificial  refrigeration  has  become 
indispensable  for  the  purpose  of  separating  the  parafflne 
wax  and  refining  the  oil.  Stearline,  India  rubber  works, 
eto.,  can  no  longer  be  without  artificial  refrigeration. 

DAIRY  REFRIGERATION. 

In  the  dairy  practice,  the  cooling  and  freezing  of 
milk,  in  butter  making,  etc.,  there  is  a  great  future  for 
artificial  refrigeration. 

Eefrigeration  has  also  been  patented  for  the  special 
purpose  of  freezing  the  water  out  of  milk  in  order  to 
concentrate  the  same  without  heat. 

REFRIGERATION  IN  GLUE  WORKS. 

Some  glue  manufacturers  have  found  it  to  their  in- 
terest to  improve  their  product  by  drying  their  gelatine 
in  rooms  artificially  refrigerated,  thus  permitting  them 
to  use  glue  solutions  less  concentrated. 

VARIOUS  USES  OF  REFRIGERATION. 

Manufacturers  of  oleomargarine,  of  butterine,  soap, 
chocolate,  etc.,  derive  great  benefit  from  artificial  refrig- 
eration. For  seasoning  lumber  it  is  also  employed  to 
some  extent  already. 

Skating  rinks,  ice  railways,  etc.,  are  kept  in  working 
order  all  the  year  now  by  artificial  refrigeration. 

Young  trees  are  kept  in  cold  storage  to  hold  back 
unseasonable  and  premature  growth. 

The  preservation  of  the  eggs  of  the  silkworm,  so  as 
to  make  the  eclosion  of  the  eggs  coincide  with  the  ma- 
turity of  leaves  of  the  mulberry  tree  has  also  become  a 
subject  of  artificial  refrigeration. 

Many  transatlantic  vessels  are  equipped  with  gigantic 
refrigerating  apparatus  to  enable  them  to  transport  per- 
ishable goods,  chiefly  meat,  but  also  fruits,  beer,  etc. 

In  dynamite  factories  for  maintaining  the  dynamite 
at  a  low  temperature  during  the  process  of  nitrating. 

In  manufactories  of  photographic  accessories,  for 
cooling  gelatine  dry  plates. 

In  the  establishments  of  wine  growers  and  merchants 
for  reducing  the  temperature  of  the  must  or  un fer- 
mented wine,  and  for  the  obtainment  of  an  equable  tem- 
perature in  the  cellars,  etc. 

Wool  and  woolen  garments,  as  likewise  furs  and 
peltry,  are  preserved  from  the  attacks  of  moths  by  artifi- 
cial refrigeration. 


BEFRICKERATION  FOR  PACKING  HOtfSES.  2lO 

Beds  in  summer  time  may  be  cooled  by  pans  filled 
with  ice  in  the  same  way  as  they  are  warmed  by  warm 
icg  pans  in  winter.  This  cooling  of  beds  is  said  to  pro- 
duce immediate  sleep  and  rest,  and  is  especially  recom- 
mended in  cases  of  insomnia  and  other  afflictions. 

Decorative  effects,  quite  novel  and  artistic,  to  adorn 
the  dining  table,  etc.,  may  be  produced  by  freezing  flow- 
ers, fishes,  etc.,  tastefully  grouped  in  clear  crystal  ice 
blocks  of  convenient  shapes. 

For  refrigeration  of  dwellings,  hospitals,  hotels,  pub- 
lic institutions,  etc.: 

This  subject  has  been  much  written  about,  but  in 
the  practice  of  refrigerating  dwellings  and  hotels  during 
the  hot  season  little  progress  has  been  made  so  far,  many 
being  of  the  opinion  that  it  would  be  too  expensive  for 
general  use.  While  this  may  be  so,  there  is  doubtless  a 
great  field  open  in  this  direction  for  the  application  of 
refrigeration  in  those  cases  in  which  expense  is  a  second- 
ary consideration. 

The  value  of  ice  in  therapeutics  is  generally  recog- 
nized. From  among  the  more  recent  applications  in  this 
direction  may  be  mentioned  the  following :  Ice  is  used 
for  the  induction  of  failing  respiration  by  rubbing  slowly 
the  mucous  membrane  of  the  lips  and  mouth  with  a  piece 
of  ice  to  the  rhythm  of  normal  respiration. 

Ice  is  said  to  moderate  inflammation  of  the  brain  or 
its  membranes,  and  also  the  severe  headache  of  the  early 
stages  of  acute  fevers,  also  to  relieve  the  pain  and  vomit- 
ing in  cases  of  ulcer  or  cancer  of  the  stomach.  It  is 
also  excellent  for  the  sore  throat  of  fevers,  and  in  cases  of 
diphtheria.  Sucked  in  small  pieces,  it  checks  secretions 
of  the  throat.  Ice  also  arrests  hemorrhage  in  a  measure. 

Artificial  refrigeration  is  also  very  extensively  used 
m  the  shipping  of  all  sorts  of  produce,  especially  meat, 
eggs,  etc.,  and  the  refrigerating  installations  in  vessels 
crossing  the  ocean,  and  in  railroad  cars  crossing  the 
plains,  are  subjects  of  special  study  and  detail  which  it 
would  be  beyond  the  scope  of  this  book  to  enter  into 
here.  We  may  add,  though,  that  the  refrigeration  during 
transit  is  not  confined  to  railroad  cars  and  steamboats, 
but  that  small  delivery  wagons  for  meat,  eggs,  etc.,  are 
now  constructed  with  special  reference  to  the  keeping  of 
their  refrigerated  contents  until  delivered  to  the  con- 
sumer or  retailer. 


220  MECHANICAL  REFRIGERATION-. 

In  distilleries  for  keeping  the  spirits  in  the  store 
tanks  cool  during  hot  weather,  and  thereby  obviating 
the  very  serious  loss  that  is  otherwise  experienced 
through  evaporation. 

In  chocolate  and  cocoa  manufactories  to  enable  the 
cooling  room  to  be  maintained  at  a  low  temperature  in 
summer,  and  the  process  to  be  worked  continuously  all 
the  year  around.  A  great  saving  is  likewise  effected  by 
the  rapid  solidification  which  is  rendered  possible,  and 
the  waste  thus  avoided;  and  furthermore,  as  the  choco- 
late leaves  the  molds  readily  and  intact,  a  considerably 
fewer  number  of  the  latter  are  required  to  do  the  same 
amount  of  work. 

In  sugar  factories  and  refineries  for  the  concentra- 
tion of  saccharine  juices  and  solutions  by  freezing  or 
congealing  the  water  particles,  which  are  then  removed, 
leaving  the  residuum  of  a  greater  strength. 

In  India  rubber  works  for  the  curing  and  hardening 
of  India  rubber  blocks,  thereby  facilitating  the  cutting 
of  same  into  sheets  for  manufacture  of  various  elastic 
articles.  The  material  in  that  state  admitting  of  its  be- 
ing worked  up  in  a  much  superior  manner,  and,  more- 
over, at  a  far  lower  cost 

REFRIGERATION  IN  CHEMICAL  WORKS. 

Some  of  the  chemical  industries  in  which  artificial 
refrigeration  is  extensively  used  have  been  mentioned  al- 
ready, and  to  these  may  be  added  ash  works,  asphalt  and 
tar  distilleries,  nitroglycerine  works,  etc.  In  fact,  all 
chemical  operations  which  depend  largely  on  differences 
in  temperature,  notably  all  those  involving  crystalliza- 
tion processes,  can  in  most  cases  be  greatly  assisted  by 
the  use  of  artificial  refrigeration.  This  is  particularly 
true  of  substances  which  it  is  difficult  to  obtain  in  a  pure 
state,  and  which  do  not  pass  into  the  solid  state,  except 
at  very  low  temperature.  To  successfully  purify  such  sub- 
stances— and  there  are  a  great  many  of  them — artificial 
refrigeration  is  the  most  valuable  auxiliary,  and  very  re- 
markable results  have  been  obtained  already  in  this  direc- 
tion. The  most  successful  purification  of  glycerine  is  an 
instance  of  this  kind.  Chloroform  is  another  still  more  re- 
markable example.  This  substance,  although  considered 
pure,  was  nevertheless  of  a  very  unstable  character.  Time, 
action  of  light,  heat  and  other  unavoidable  conditions, 


REFRIGERATION  FOR  PACKING  HOUSES.  221 

caused  its  degeneration,  until  it  was  shown  by  Pictet  that 
an  absolutely  pure  article  of  chloroform  could  be  obtained 
by  crystallizing  the  same  at  a  temperature  of  about — 90°. 
This  is  a  very  low  temperature,  considering  practical 
possibilities  of  the  present  day,  but  it  accomplishes  the 
object;  and  there  are  many  more  equally  useful  applica- 
tions not  yet  thought  of,  or  beyond  the  reach  of  practical 
refrigeration  at  present. 

CONCENTRATION  OF  SULPHURIC  ACID. 

The  concentration  of  sulphuric  acid,  which  is  accom- 
plished in  expensive  platinum  vessels,  can  be  accom- 
plished, according  to  Stahl,  in  leaden  vessels,  if  artificial 
refrigeration  is  used  to  crystallize  the  strong  acid,  which 
can  then  be  separated  from  the  weak  mother  acid. 
Another  interesting  chemical  change  brought  about  by 
artificial  refrigeration  is  the  decomposition  of  the  acid 
sulphate  of  soda  into  neutral  salt  and  free  sulphuric  acid. 

DECOMPOSITION  OF  SALT  CAKE. 

Another  interesting  application  of  refrigeration  in 
chemical  manufacturing  is  the  decomposition  of  the  so- 
called  salt  cake  (acid  sulphate  of  soda)  into  sulphuric 
acid  and  neutral  sulphate  of  soda,  which  takes  place  when 
a  watery  solution  of  the  said  salt  is  subjected  to  a  low 
temperature. 

PIPE  LINE  REFRIGERATION. 

In  many  cities  refrigeration  is  furnished  to  hotels, 
butchers,  restaurants,  private  houses,  etc.,  by  a  pipe  line 
which  carries  liquid  ammonia;  another  pipe  line  return- 
ing the  expanded  ammonia  to  the  central  factory,  at 
which  a  large  supply  of  liquid  ammonia  is  kept  in  store 
to  regulate  inequalities  in  the  demand  for  refrigeration. 

REFRIGERATION  AND  ENGINEERING. 

When  making  excavations  in  loose  soil,  it  has  been 
found  expedient  to  freeze  the  ground  by  artificial  refrig- 
eration, and  this  artifice  is  now  extensively  applied  in 
mining  operations,  in  the  sinking  of  bridge  piers,  in  tun- 
neling through  loose  or  wet  soil,  etc. 

One  of  the  greatest  pieces  of  engineering  with  the 
aid  of  refrigerating  machinery  was  accomplished  about 
two  years  ago  in  the  opening  of  a  coal  mine  in  Anzin, 
France.  The  coal  was  over  1,500  feet  below  the  surface, 
and  below  strata  strongly  saturated  with  water,  and  im- 
passable without  artificial  solidification. 


222  MECHANICAL  REFRIGERATION. 

CHAPTER  IX.—  THE  ABSORPTION  SYSTEM. 

THE  CYCLE  OF  OPERATIONS. 

As  in  the  compression  system  of  ammonia  refrigera- 
tion, the  operations  performed  in  the  absorption  system 
constitute  what  has  been  termed  a  cycle  of  operations, 
the  working  medium,  ammonia  liquor,  returning  period- 
ically to  its  initial  condition,  at  least  theoretically  so. 

A  COMPOUND  CYCLE. 

It  is,  however,  not  a  reversible  cycle,  but  rather  two 
cycles  merged  into  one,  or  a  compound  cycle.  The  anhy- 
drous ammonia  after  leaving  the  still  at  the  top,  passes 
through  the  analyzer,  condenser,  receiver  and  refrigera- 
tor to  the  absorber,  where  it  meets  the  weak  liquor  com- 
ing through  the  heater  and  exchanger  from  the  still,  and 
t"ien  after  having  been  absorbed  by  the  latter,  passes  as 
rich  liquor  from  the  absorber  through  the  ammonia  pump 
to  the  exchanger,  and  through  the  heater  to  the  still, 
entering  the  latter  by  first  passing  through  the  analyzer, 
generally  located  at  the  top  of  the  still. 

APPLICATION  OF  FIRST  LAW  TO  CYCLE. 

Owing  to  the  complexity  of  the  operations  of  the 
double  or  compound  cycle,  its  theoretical  working  condi- 
tions cannot  be  expressed  by  so  simple  a  formula  as  in 
the  case  of  a  reversible  cycle.  Nevertheless,  the  tenets 
of  the  first  law  of  thermodynamics  apply  in  this  case  also, 
and  therefore  the  heat  and  work  which  is  imparted  to  the 
working  substance  while  performing  the  operations  of 
one  period  of  the  cycle  must  be  equal  or  equivalent  to  the 
heat  and  work  which  are  withdrawn  during  the  same 
period  —  all  quantities  to  be  expressed  by  the  same  kind 
of  units. 

EQUATION  OF  ABSORPTION  CYCLE. 

Hence,  if  Wt  is  the  heat  imparted  to  the  liquid  in 
the  still,  and  W2  the  heat  imparted  to  the  anhydrous 
ammonia  in  the  refrigerator,  and  W3  the  heat  equivalent 
of  the  work  of  ammonia  pump,  we  find— 


Ht  being  the  heat  withdrawn  from  the  anhydrous 
ammonia  in  the  condenser,  and  H2  being  the  heat  with- 
drawn from  the  working  substance  in  the  absorber. 


THE   ABSORPTION  SYSTEM.  223 

As  all  the  quantities  in  the  above  equation  (besides 
Wi)  can  be  readily  determined,  it  enables  us  to  find,  if 
not  a  simple  at  least  an  artless  expression  for  Wl  (i.  e., 
the  heat  which  must  be  imparted  to  the  liquid  in  the 
still). 

WORKING  CONDITIONS  OF  SYSTEM. 

For  the  purpose  of  determining  the  theoretical  values 
of  the  quantities  which  determine  the  efficiency  of  an 
absorption  machine,  we  make  the  following  stipulations 
which,  we  hold,  are  such  as  to  be  within  the  theoretical 
possibility  of  realization,  although  practically  they  have 
not  as  yet  been  fully  realized,  viz.: 

That  the  apparatus  is  provided  with  efficient  analyzer 
and  rectifier,  so  that  the  ammonia  when  entering  the 
condenser  is  practically  in  an  anhydrous  condition. 

That  the  poor  liquor  when  entering  the  absorber  is 
only  5°  warmer  than  the  rich  liquor  when  leaving  the 
absorber. 

That  all  the  heat  of  the  poor  liquor,  except  that 
brought  into  the  absorber,  is  imparted  to  the  rich  liquor 
on  its  way  to  the  still  in  the  exchanger. 

That  the  uncompensated  heat  transfers  from  the  at- 
mosphere to  the  colder  portions  of  the  plant,  and  from  the 
warmer  portions  of  the  plant  to  the  atmosphere,  are  so 
well  guarded  against  that  they  may  be  neglected  in  this 
connection. 

HEAT  ADDED  IN  REFRIGERATION. 

The  above  premises  being  granted,  the  different  items 
of  the  above  equation  are  readily  expressed.  The  heat, 
W2,  added  to  the  working  fluid  in  the  expansion  or  re- 
frigerating coils,  is  theoretically  equal  to  tbe  amount  of 
refrigeration  which  is  produced  by  its  evaporation. 

The  refrigeration,  r,  in  B.  T.  units  which  may  be  pro- 
duced by  the  vaporization  of  one  pound  of  anhydrous 
ammonia  in  an  absorption  machine  is  the  same  as  in  a 
compression  machine,  and  is  therefore  expressible  by  the 
same  formula: 

r  =  hl  —  (t  —  tt  }s  units, 

hi  being  the  heat  of  volatilization  of  one  pound  of  am- 
monia at  the  temperature  tn  of  the  refrigerator;  t  is  the 
temperature  of  the  liquid  anhydrous  ammonia,  i.  e.,  the 
temperature  of  the  condenser,  and  s  the  specific  heat  of 
ammonia. 


224  MECHANICAL  REFRIGERATION. 

For  the  purpose  of  this  calculation  the  temperature 
of  the  outgoing  condenser  water  may  be  taken  for  £,  but 
in  order  to  find  the  maximum  theoretical  refrigerating 
effect,  the  temperature  of  the  incoming  condenser  water, 
or  rather,  about  5C  added  to  that,  should  be  taken  for 
t,  as  the  liquid  anhydrous  ammonia  can  be  cooled  to  that 
degree  by  the  condenser  water.  This  also  applies  to  the 
same  calculation  for  compression  system. 

HEAT  INTRODUCED  BY  PUMP. 

The  heat,  W3,  imparted  to  the  working  medium  by 
the  operation  of  the  ammonia  pump  is  equivalent  to  the 
work  required  to  lift  the  rich  liquor  from  the  pressure  of 
the  absorber  to  that  of  the  still.  It  is  not  a  very  im- 
portant quantity  in  this  connection,  and  may  be  neglected 
in  approximate  calculations.  However,  it  may  be  de- 
termined by  the  formula: 


for  each  pound  of  anhydrous  ammonia  which  is  volatil- 
ized in  the  expander.  In  this  formula  P2  stands  for  the 
number  of  pounds  of  rich  liquor  which  must  be  moved 
for  every  pound  of  ammonia  volatilized  in  the  expander; 
and  z  and  z^  being  in  feet  the  heights  of  columns  of  water 
corresponding  to  the  pressure  in  the  still  and  pressure 
in  absorber,  respectively.  S  represents  the  specific  grav- 
ity of  the  rich  liquor,  and  772  the  equivalent  of  the  heat 
unit  in  foot-pounds.  In  exact  calculations  the  heat  due 
to  friction  of  pumps  should  be  added. 

RICH  LIQUOR  TO  BE  CIRCULATED. 

The  number  of  pounds  of  rich  liquor,  P2,  which  must 
pass  the  ammonia  pumps  in  order  that  one  pound  of 
liquid  anhydrous  ammonia  may  be  disposable  in  the  ex- 
pander or  refrigerator  coils,  depends  on  the  concentra- 
tion or  strength  of  the  poor  and  rich  ammonia  liquor, 
and  if  the  percentage  strength  of  the  former  be  a,  and 
that  of  the  latter  be  c,  we  find— 

P  100        _  (100-a)     100          ]b 

(100—  c)  a  (100—  a)  c—  (100—  c)  a 

c~~    (100—  a) 


THE    ABSORPTION   SYSTEM.  225 

STRENGTH  OF  AMMONIA  LIQUOR. 

The  percentage  strength  of  the  rich  liquor  depends 
largely  on  the  construction  of  the  absorber.  Theoretically 
it  is  determined  by  the  temperature  at  which  it  leaves 
the  absorber  and  the  pressure  in  the  latter  as  shown  in 
the  tables  on  solutions  of  ammonia  given  by  Starr,  pages 
96  and  97. 

The  lowest  possible  percentage  strength  of  the  poor 
liquor  depends  in  a  similar  manner  on  the  temperature 
and  pressure  in  the  still,  but  is  also  greatly  affected  by 
the  constructive  detail  and  operation  of  this  appliance. 

HEAT  REMOVED  IN  CONDENSER. 

The  amount  of  heat,  H^  which  is  taken  away  from 
the  working  substance  in  the  condenser,  while  one  pound 
of  vapor  is  condensed  into  liquid  ammonia,  is  equal  to  the 
latent  heat  of  volatilization  of  that  amount  of  ammonia 
at  the  temperature  of  the  condenser  (temperature  of  out- 
going condenser  water),  and  may  be  readily  obtained 
from  the  table  on  saturated  ammonia,  page  92. 

HEAT  REMOVED  IN  ABSORBER. 

The  amount  of  H2  which  must  be  withdrawn  from 
the  working  liquid  in  the  absorber  is  composed  of  differ- 
ent parts,  viz.: 

The  heat  developed  by  the  absorption  of  one  pound 
of  ammonia  in  the  poor  liquor,  Hn  . 

The  heat  brought  into  the  absorber  by  a  correspond- 
ing quantity  of  poor  liquor,  Hg  . 

The  negative  heat  brought  into  the  absorber  by  one 
pound  of  the  refrigerated  ammonia  vapor,  Hy. 

Hence  we  find— 

H2  =  Hn-^-Hg~  Hv  units. 

HEAT  OF  ABSORPTION. 

The  heat  developed  by  the  absorption  of  ammonia 
vapor  in  the  poor  liquor  may  be  obtained  after  the  form- 
ula given,  pages  99  and  100,  viz.: 


<?,  =  9256-  units. 

n 

In  this  formula  n  stands  for  the  number  of  pounds 
of  water  contained  in  the  poor  liquor  for  each  pound  of 
ammonia,  and  1  -f-  h  stands  for  the  number  of  pounds  oi 
ammonia  contained  in  the  rich  liquor  for  every  n  pound 


226 


MECHANICAL  REFRIGERATION": 


of  ammonia.  Under  these  suppositions  Q3  stands  for 
the  number  of  heat  units  developed  by  the  absorption  of 
b  pounds  ammonia  vapor,  or  the  heat  developed  by  one 


pound  is — 


Hn 


^-units. 


The  last  two  formulas  may  be  united,  to  give  a  sim- 
pler expression  for  the  amount  of  heat  developed  when 
one  pound  of  ammonia  is  dissolved  in  a  sufficient  quan- 
tity of  poor  liquor,  containing  one  pound  of  ammonia  to 
n  pounds  of  water,  in  order  to  obtain  a  rich  liquor  which 
will  contain  b  -}-  1  pound  of  ammonia  for  each  n  pound  of 
water.  The  formula  then  reads— 


n  =  925  _ 


units. 


The  amount  of  heat  developed  by  the  absorption  of 
one  pound  of  ammonia  in  some  cases  of  different  strength 
of  poor  and  rich  liquor,  calculated  after  the  foregoing 
formula,  is  given  in  the  subjoined  table,  together  with 
the  number  of  pounds  of  rich  liquor  that  must  be  moved 
for  each  pound  of  ammonia  evaporated  in  the  refrig- 
erator. 


I 

Ammonia  in 
poor  liquor,  per 
cent. 

Ammonia  in 
rich  liquor,  per 
cent. 

Heat  of  absorp- 
tion by  one 
pound  of  am- 
monia in  units. 

Pounds    of    rich 
liquor  for  each 
pound   of  active 
ammonia. 

a 

c 

Hn 

P2 

10 

25 

812 

6.0 

10 

36 

828 

3.45 

12 

35.5 

828 

3.74 

14 

25 

854 

7.8 

15 

35 

811 

4.25 

17 

28.75 

840 

7.0 

20 

25 

840 

16.0 

30 

33 

819 

6.1 

20 

40 

795 

4.0 

HEAT  INTRODUCED  BY  POOR  LIQUOR. 

The  number  of  pounds  of  poor  liquor  which  enters 
the  absorber  for  each  pound  of  active  ammonia  vapor  is 
equal  to  the  rich  liquor  less  one,  this  being  the  amount 
or  weight  of  ammonia  withdrawn,  and  therefore  the  heat,, 
.Hg,  which  enters  the  absorber  with  that  amount  of  poor 
liquor,  when  its  temperature  is  5°  above  that  of  rich  liquor 
leaving  the  absorber,  is — 

HK  =  (P2  — 1)5X  S  units, 

S  being  the  specific  heat  of  the  poor  liquor,  which  may  be 
taken  at  1. 


THE    ABSORPTION  SYSTEM.  227 

NEGATIVE  HEAT  INTRODUCED  BY  VAPOR. 

The  negative  heat,  Hv,  brought  into  the  absorber  with 
every  pound  of  ammonia  vapor  is— 

Hv  =  (t—ti]  0.5  units, 

t  being  the  temperature  of  the  strong  liquor  leaving  the 
absorber,  and  i,  being  the  temperature  in  refrigerator 
coils. 

HEAT  REQUIRED  IN  GENERATOR. 

From  the  above  it  is  evident  that  the  strength  of 
strong  and  weak  liquor,  the  pressure  in  still  and  absorber, 
and  all  other  quantities,  depend  in  a  perfectly  constructed 
plant  in  the  last  end  on  the  temperature  of  cooling  water 
and  brine.  Accordingly,  it  would  be  possible  to  express 
the  heat  required  in  the  still  or  generator  as  a  function 
of  these  temperatures,  but  the  formula  required  to  do 
this  would  be  so  complicated  as  to  be  without  any  prac- 
tical value,  nor  would  it  possess  any  theoretical  signifi- 
cance. 

As  all  the  quantities  (excepting  W^  )  of  the  equation 
of  the  absorption  cycle  can  be  determined  numerically  in 
the  manner  shown,  the  quantity,  TF^or  the  heat  required 
in  the  generator,  can  be  readily  determined  after  the 
formula  — 


WORK  DONE  BY  AMMONIA  PUMP. 

The  power,  F  (in  foot-pounds),  required  to  run  the 
ammonia  pump  is  theoretically  expressed  by  the  formula: 

F=P*(Z~Z*]  foot-pounds, 

for  every  pound  of  active  ammonia,  *.  e.,  anhydrous  am- 
monia evaporating  in  refrigerator.    (See  page  224.) 

ANHYDROUS  AMMONIA  REQUIRED. 

The  number  of  pounds,  Plt  of  anhydrous  ammonia 
required  to  circulate  to  produce  a  certain  refrigerating 
effect,  say  ra  tons  in  twenty-four  hours,  is— 

m  X  284000 
f  >  =  -  -  —  ~  pounds. 

OF  THE     **A 

UNIVERSITY   } 


228  MECHANICAL  REFRIGERATION. 

HORSE  POWER  OF  AMMONIA  PUMP. 

The  power,  Ftt  to  run  the  ammonia  pump  while  pro- 
ducing a  refrigerating  effect  of  m  tons  in  twenty-four 
hours,  is,  therefore— 


and  expressed  in  horse  power  F2,  S  being  taken  equal 
to  1: 

F  -  -P«XmX  384000  X(g-gi 

*2~         rx  33000X24X60 

33,000  being  the  equivalent  of  a  horse  power  in  foot- 
pounds per  minute. 

The  formula  for  F2  may  be  simplified  to— 

•_       P2X  m(z  —  zl)  0.006, 

F2  =  —          -  -         —horse  power. 

This  is  the  horse  power  required  theoretically,  to 
which  must  be  added  the  friction,  clearance  and  other 
losses  of  the  pump,  as  well  as  of  the  engine  which  ope- 
rates the  pump,  to  find  the  actual  power  and  the  equiva- 
lent amount  of  steam  required  for  this  purpose. 

AMOUNT  OF  CONDENSING  WATER. 

The  water  required  in  the  condenser  expressed  in 
gallons,  Gr,  for  a  refrigerating  capacity  of  m  tons  in 
twenty  -four  hours  is  — 

„      /H  X  m  X  284000 


or  approximately  per  minute  in  gallons,  Gt  — 


in  which  formula  h  t  is  the  latent  heat  of  volatilization 
of  ammonia  at  the  temperature  of  the  outgoing  con- 
denser water,  t,  and  tt  the  temperature  of  the  outgoing 
condenser  water;  r  is  the  refrigerating  effect  of  one  pound 
of  ammonia. 

WATER   REQUIRED  IN  ABSORBER. 

The  amount  of  heat  to  be  removed  in  absorber  for 
each  pound  of  ammonia  vaporized  in  refrigerator  being 
Ifj,  as  found  in  the  foregoing,  the  amount  of  water  re- 


THE    ABSORPTION  SYSTEM.  229 

quired  iii  absorber  for  a  refrigerating  capacity  of  m  tons 
in  twenty-four  hours,  expressed  in  gallons,  G2,  is— 
„      .  H2  X  m  X  284000 


or  expressed  per  minute  in  gallons,  Gr8  — 
^   _H2  XWX24 
r(t-tt) 

ECONOMIZING  WATER. 

When  water  is  scarce  or  expensive,  the  same  water 
after  it  has  been  used  in  condenser  is  used  in  the  absorber, 
which,  of  course,  raises  the  temperature  of  the  ingoing 
and  outgoing  absorber  water  correspondingly.  The 
water  may  also  be  economized  by  using  open  air  con- 
densers or  by  re-  cooling  the  same  by  gradation,  etc. 

ECONOMIZING  STEAM. 

As  the  poor  liquor  is  less  in  volume  and  weight  than 
the  rich  liquor,  it  cannot  possibly  heat  the  latter  to  the 
temperature  of  still,  other  reasons  notwithstanding.  For 
this  reason  the  waste  steam  of  the  ammonia  pump  may 
be  used  to  still  further  heat  the  rich  liquor  on  its  way  to 
the  generator  after  it  has  left  the  exchanger.  This  is 
done  in  the  heater,  and  the  heat  so  imparted  to  the  work- 
ing fluid  should  be  deducted  from  the  heat  to  be  fur- 
nished to  the  generator  direct  in  theoretical  estimates. 
The  condensed  steam  from  generator  may  be  returned 
to  boiler  if  it  is  not  used  for  ice  making. 

AMOUNT  OF  STEAM  REQUIRED. 

The  theoretical  amount  of  steam  required  in  gener- 
ator expressed  in  pounds  P5  per  hour  for  a  refrigerating 
capacity  of  m  tons  in  twenty-four  hours  is  approximately 
found  after  the  formula 

„        Wi  X  m  X  284000 

24  X  r  X  ha 

h8  being  the  latent  heat  of  steam  at  the  pressure  of  the 
boiler,  or,  closer  still,  at  the  temperature  of  the  generator. 

As  stated  in  the  beginning,  these  calculations  are 
based  on  ideal  conditions,  which  are  never  met  with  in 
practical  working,  and  therefore  the  quantities  found 
must  be  modified  accordingly,  and  the  theoretical 
amount  of  steam  as  found  must  be  increased  by  from  20 
to  40  per  cent,  and  even  more,  to  arrive  at  the  facts  jp 
most  practical  cases, 


230  MECHANICAL  REFRIGERATION. 

The  amount  of  steam  used  by  the  ammonia  pump 
must  be  added  to  the  above:  It  is  generally  about  £  to  | 
of  the  steam  used  in  the  generator. 

ACTUAL  AND  THEORETICAL  CAPACITY. 

In  order  to  compare  the  actual  refrigerating  capacity 
of  an  absorption  plant  with  the  theoretical  capacity,  the 
amount  of  steam  used  in  the  still,  as  well  as  the  amount 
of  rich  liquor  circulated  by  the  ammonia  pump,  may  be 
taken  as  a  basis.  The  first  case  is  practically  disposed  of 
in  the  foregoing.  In  the  latter  case  the  amount  of  liquid 
moved  by  the  ammonia  pump  is  equal  to  its  capacity  per 
minute,  which  is  found  by  calculation,  as  in  the  case  of  a 
compressor,  and  reduced  to  pounds  per  minute.  If  this 
quantity  is  called  O,  and  if  P2  is  the  number  of  pounds  of 
rich  liquor  which  must  be  circulated  for  each  pound  of 
active  anhydrous  ammonia,  as  found  from  the  strength 
of  the  poor  and  rich  liquor  (see  foregoing  table),  the  refrig- 
erating capacity  of  the  machine,  -K,  should  be  — 


R=  -73—  units  per  minute. 

*  z 

The  theoretical  and  actual  heat  balances  can  also  be 
compared  by  determining  the  heat  removed  in  the  con- 
denser and  absorber,  as  well  as  the  heat  brought  into  the 
refrigerator  and  to  the  generator  by  actual  measurement. 

SIMPLER  EXPRESSION  FOR  Wx. 

If  we  neglect  the  work  of  the  liquor  pump  and 
assume  that  the  poor  liquor  arrives  at  the  absorber  at 
the  absorber  temperature,  we  can  express  the  amount  of 
heat  W^  theoretically  required  in  the  generator  for  each 
pound  of  anhydrous  ammonia  circulated  by  the  formula  — 

Wt  =  Hn  —  (hz—h)  units, 

h2  being  the  latent  heat  of  volatilization  of  ammonia  at 
the  temperature  of  the  absorber,  and  ht  the  latent  heat 
of  volatilization  of  ammonia  at  the.  temperature  of  the 
condenser. 

It  is  frequently  argued  that  an  equivalent  of  the 
whole  heat  of  absorption  must  be  furnished  to  the  gen- 
erator, but  this  is  only  the  case  (theoretically  speaking) 
when  the  temperature  of  the  absorber  is  equal  to  Unit  of 
the  condenser, 


THE  ABSORPTION  SYSTEM.  231 

EXPRESSION  FOR  EFFICIENCY. 

The  maximum  theoretical  efficiency  J5?,  of  an  absorp- 
tion machine  may  be  expressed  in  accordance  with  the 
above. 

r        frt-(t-*t)* 
* 


and  if  we  include  the  work  of  the  ammonia  pumps,  etc., 
we  have  also  — 


COMPARABLE  EFFICIENCY  OF  COMPRESSOR. 

In  order  to  compare  the  maximum  theoretical  effi- 
ciency of  an  absorption  plant  with  that  of  a  compression 
plant  the  foregoing  formula: 


may  be  used,  when  in  the  case  of  compression  Wt  stands 
for  the  amount  of  heat  theoretically  necessary  to  produce 
the  work  required  from  the  engine  for  the  circulation  of 
one  pound  of  ammonia. 

If  the  absolute  temperature  of  steam  entering  the 
engine  is  T,  and  that  of  the  steam  leaving  the  engine  is 
T1  ,  and  if  the  work  of  the  engine  which  operates  the  com- 
pressor is  expressed  by  Qt  (in  heat  units),  we  find  for  W^ 
the  expression— 


If  we  omit  friction  of  compressor  and  engine  and  in- 
sert for  Qi  the  theoretical  work  of  the  compressor  (page 
111)  we  find— 

Qi        (r-rjhi 

r  and  rt  being  the  absolute  temperatures  of  condenser 
and  refrigeration  respectively.    It  is  then — 

u,       hi(r  —  rJT 

and  for  the  maximum  theoretical  efficiency  of  the  com- 
pression machine,  leaving  out  friction,  etc.,  we  find — 


232 


MECHANICAL  REFRIGERATION. 


CONSTRUCTION  OF  MACHINE. 

The  construction  details  of  the  absorption  plants 
vary  so  much  that  in  this  place  we  can  only  give  the 
general  outlines  touching  the  appliances  and  contriv- 
ances which  by  a  concert  of  action  make  up  the  refrig- 
erating effect.  The  dimensions  of  parts  vary  also  very 
greatly,  and  those  given  in  the  following  paragraphs  and 
tables  are  based  on  data  reported  from  machines  in  actual 
operation  where  not  otherwise  stated. 

THE  GENERATOR. 

The  generator,  retort  or  still  is  generally  an  upright 
cylinder  heated  with  a  steam  coil  in  which  the  concen- 
trated or  rich  liquor  is  heated.  The  rich  liquor 
passes  in  at  the  top  and  leaves  at  the  bottom.  The  retort 
and  dome  is  made  of  steel  plate,  sometimes  of  cast 
iron;  and  this  vessel,  the  same  as  other  parts  containing 
ammonia  gas,  should  be  capable  of  withstanding  a  liquid 
pressure  of  400  pounds  per  square  inch. 

SIZE  OF  GENERATOR. 

The  size  of  the  still  or  generator  depends  on  the  size 
of  the  machine,  and  for  a  10-ton  machine  (actual  ice 
making  capacity)  is  about  two  to  two  and  one-half  feet 
wide  and  fifteen  to  eighteen  feet  high,  and  a  little  over 
half  of  this  height  is  generally  occupied  by  the  steam 
coil.  An  English  author  gives  the  following  table  of  di- 
mensions for  generators  or  stills  of  absorption  machines, 
but  they  appear  rather  small  compared  with  American 
structures  for  the  same  object : 


Ice  Made  in 

Gallons  of  .880 

SIZE  OF  GENERATOR. 

24  Hours. 

Ammonia. 

Diameter. 

•Length. 

1 

27 

13.  5  inches. 

5  feet  6  inches. 

.    2 

54 

17.0 

6     "     0 

3 

80 

21.5 

6     "     0 

4 

108 

22.5 

6     "     6 

6 

162 

22.5 

10     "     6 

8 

216 

25.0 

12     "     0 

10 

252 

26.0 

12     "     0 

12 

270 

28.0 

13     "     0 

15 

405 

29.5 

14     "     0 

24 

540 

35.0 

14     "     0 

BATTERY  GENERATOR. 

Generators  have  also  been  constructed  on  the  battery 
plan,  three  or  more  cylinders  being  connected  td  form 
one  generator,  the  rich  liquor  passing  gradually  from 
the  first  cylinder  to  the  last,  which  it  leaves  as  poor 
liquor.  In  this  manner  it  is  possible  to  attain  a  wider 


THE  ABSORPTION  SYSTEM.  233 

difference  between  the  strength  of  the  rich  and  poor 
liquor,  it  is  claimed. 

COILS  IN  RETORT. 

The  heating  coils  in  retort  or  still  are  placed  in  the 
lower  part  ,of  the  retort,  and  consist  of  one  or  more 
spiral  coils  of  pipe  placed  concentrically.  According  to 
Coppet,  their  connections  should  be  at  both  the  bottom 
entrance  and  exit,  and  should  be  made  right  and  left 
handed,  the  object  being  to  prevent  the  steam  (when 
rushing  down  in  the  coils)  from  imparting  a  gyrating 
motion  to  the  liquor,  thus  shaking  the  retort.  The  coils 
should  be  made  of  purest  charcoal  iron,  free  from  defects 
or  spots,  as  the  hot  ammonia  liquor  is  very  apt  to  pene- 
trate such  bad  places  and  cause  leaks.  The  space  in  still 
occupied  by  steam  coil  should  always  contain  ammonia 
liquor,  so  that  the  coil  is  never  exposed  to  the  vapors. 
For  this  reason  a  gauge  is  provided,  which  shows  the 
height  of  the  liquor  in  the  generator.  As  a  further  pre- 
caution there  is  placed  above  the  steam  coils  an  in- 
verted cone,  with  a  large  central  opening,  placed  so  that 
the  liquor  will  be  deflected  to  the  center  of  still,  and  not 
fall  upon  the  coils,  if  ever  the  liquor  should  stand  below 
them.  A  valve  is  provided  at  the  bottom  of  the  retort  to 
empty  same,  if  necessary,  and  also  one  at  the  poor  liquor 
pipe  leading  to  exchanger.  The  heating  surface  of  the 
coil  in  retort  varies  considerably,  and  for  aJLO-ton  ma- 
chine it  covers  from  eighty  to  100  feet. 

THE    ANALYZER. 

In  the  upper  part  of  the  still  the  so  called  analyzer 
is  located.  In  it  the  rich  liquor  is  made  to  pass  over 
numerous  shelves  or  disks  into  corresponding  basins,  over 
which  it  runs  in  a  trickling  shower  from  one  disk  through 
the  next  basin  over  the  following  disk,  and  so  on,  until 
it  reaches  the  top  of  the  boiling  liquid  in  retort.  While 
the  rich  liquor  runs  downward  over  these  devices,  the 
vapor  from  the  retort  passes  them  in  its  upward  course  and 
constantly  meeting  the  rich  liquid  over  an  extended  area, 
is  enriched  in  ammonia,  and  deprived  of  water.  Thus 
the  ammonia  vapor  is  rendered  almost  free  of  water  when 
it  reaches  the  top  of  the  analyzer.  At  the  same  time  the 
temperature  of  the  rich  ammonia  liquor  is  increased 
from  about  150°  to  170°,  at  which  it  reaches  the  analyzer, 
to  about  20CP,  more  or  less,  when  it  reaches  the  body  of 
liquor  in  the  retort. 


234 


MECHANICAL  REFRIGERATION". 


The  passages  in  the  analyzer  must  be  amply  large  for 
the  passage  of  water  and  ammonia  vapor  in  opposite 
directions  In  order  to  avoid  foaming,  overloading,  etc. 
The  best  iron  or  steel  plate  must  be  used  in  the  construc- 
tion of  the  analyzer.  As  also  stated  elsewhere,  galvan- 
ized iron  pipes  and  zinc  surfaces  in  general  must  be 
avoided  wherever  they  come  in  contact  with  ammonia. 
The  surface  in  the  analyzer  runs  from  fifty  to  seventy 
square  feet  in  a  10-ton  machine. 

THE  RECTIFIER. 

Frequently  the  vapor  on  its  way  from  analyzer  to 
condenser  passes  the  so  called  rectifier,  which  is  a  small 
coil  partly  surrounded  by  cooling  water,  the  lower  end  of 
which  is  connected  with  the  condenser  coil,  but  has 
also  a  liquid  outlet  to  a  separate  liquor  receiver  which 
receives  all  watery  condensation  which  may  have  formed 
in  the  rectifier.  In  this  manner  the  vapors,  when  they 
enter  the  condenser  proper,  are  as  nearly  anhydrous  as 
they  can  practically  be  made.  About  twenty-five  square 
feet  of  cooling  surface  is  allowed  in  the  rectifier  for  a 
machine  of  ten  tons  ice  making  capacity.  The  liquid 
separated  from  the  vapor  in  the  rectifier,  after  passing 
through  a  separate  cooler,  is  returned  to  the  ammonia 
pump,  whence  it  passes  back  to  the  generator  or  still. 

The  following  table,  giving  the  heating  surfaces  of 
generator  coils  and  surface  in  analyzer  and  rectifier  for 
machines  of  different  ^sizes,  is  also  given  on  English 
authority,  and  these  figures  also  fall  short  of  the  sizes 
employed  in  the  United  States : 


Size  In  Tons  of 
Ice  Made  in 
24  Hours. 

Surface  in  Gene- 
rator Coils. 

Surface  in  An- 
alyzer Disks. 

Surface  in 
Rectifier  Coil. 

Tons 

Square  Feet. 

Square  Feet. 

Square  Feet. 

2 
6 
12 
15 
30 
50 

16 
43 
81 
160 
214 
304 

14 

34 
68 
133 
169 

262 

4 
11 
20 
40 
50 
74 

THE  CONDENSER. 

The  vapor  after  leaving  the  still  or  rectifier  enters  the 
condenser  which  is  constructed  on  the  same  principles 
as  the  condenser  in  a  compression  machine.  Besides  the 
submerged  condenser  and  the  open  air  or  atmospheric 
condenser  (the  latter,  on  account  of  accessibility,  simplic- 


THE  ABSORPTION  SYSTEM.  235 

ity  and  cleansability,  now  most  generally  adopted)  it  has 
also  been  proposed  to  use  condensers  exposed  to  the  at- 
mosphere alone,  thus  to  save  the  cooling  water.  Such 
condenser  requires  a  considerable  surface,  at  least  over 
eight  times  that  of  the  submerged  condenser,  and  over 
five  times  that  of  the  atmospheric  condenser.  The  ma- 
terial for  condenser  coils,  as  well  as  for  all  other  coils  in 
the  absorption  machine,  should  be  the  very  best  iron. 

Still  another  form  of  condenser  consists  of  one  pipe 
within  another,  in  which  the  water  surrounds  the  out- 
side pipe  and  also  runs  through  the  internal  pipe,  while 
the  gas  passes  through  the  annular  space  between  the 
two  pipes.  This  is  a  very  effective  form  of  condenser, 
but  the  difficulty  of  keeping  it  clean  is  very  great,  and  it 
is  almost  impossible  when  the  water  is  liable  to  leave  a 
deposit.  For  sizes  of  condenser  coils  the  same  subject 
under  compression  machines  should  be  referred  to,  also 
the  subsequent  table  on  general  dimensions. 

LIQUID  RECEIVER,  ETC. 

The  vapors  after  having  passed  the  condenser,  reach 
the  receiver  in  a  liquid  form  and  thence  pass  through  the 
expansion  valve  to  the  coils  in  freezing  or  brine  tank. 
These  parts  of  the  plant,  their  construction  and  the  mode 
of  operating  them  are  quite  the  same  as  in  case  of  the  com- 
pression plant.  The  liquid  receiver  for  an  absorption  ma- 
chine should  be  at  least  large  enough  for  the  storage  of 
sufficient  liquid  ammonia  to  bring  the  poor  liquor  at  the 
bottom  of  the  retort  to  between  18°  and  20°  Reaumur 
when  the  machine  is  in  operation. 

THE  ABSORBER. 

In  the  absorber  the  vapor  of  ammonia,  after  having 
done  its  duty  in  the  freezing  tank  or  expansion  coils,  meets 
the  poor  liquor  coming  from  the  generator,  and  is  reab- 
sorbed  by  the  latter.  The  absorber  should  be  constructed 
in  such  a  manner  as  to  allow  the  ammonia  solution  as  it 
gets  stronger  to  meet  the  cooling  water  flowing  in  an 
opposite  direction,  so  that  the  warmer  water  cools  the 
weaker  solution  and  the  colder  water  cools  the  stronger 
solution .  In  compliance  with  this  condition  the  vapors  of 
ammonia  should  be  in  constant  contact  with  the  liquor, 
and  the  surface  of  contact  ought  to  be  of  reasonable 
area. 

This  may  be  accomplished  by  passing  the  ammonia 
and  weak  liquor  over  traps  or  disks,  similar  to  those 


236  MECHANICAL  REFRIGERATION. 

in  the  analyzer,  or  through  a  series  of  pipes  or  coils, 
where  they  are  in  constant  contact  with  each  other,  the 
pipes  being  efficiently  cooled  from  the  outside  by  water 
(spent  water  from  condenser  generally),  in  order  to 
remove  the  heat  of  solution  of  the  ammonia  as  fast  as 
it  is  formed.  Generally  the  ammonia  gas  and  the  poor 
liquor  are  mixed  together  into  a  manifold  at  the  lower 
end  of  the  coils.  The  surface  of  these  pipes  exposed  to 
the  cooling  water  in  a  tank  in  which  they  are  submerged 
(atmospheric  cooling,  as  in  the  case  of  atmospheric  con- 
densers, may  also  be  used),  is  variously  estimated  at  300 
to  500  square  feet  for  a  machine  of  ten  tons  ice  making 
capacity. 

THE   EXCHANGER. 

In  the  exchanger  the  heat  which  the  poor  liquor 
carries  away  from  the  still  should  be  imparted  to  the 
rich  liquor  on  its  way  to  the  still.  As  a  matter  of  course 
the  two  liquids  should  flow  in  opposite  directions,  so  that 
the  hottest  rich  liquid  meets  the  poor  liquid  when  it  is 
hottest,  and  the  cold  poor  liquid  meets  the  rich  liquid 
when  it  is  coldest. 

The  exchanger  is  also  to  be  made  of  the  best  sheet 
steel,  and  the  coils  within  should  be  extra  heavy,  and 
the  whole  apparatus  must  be  able  to  sustain  the  same 
pressure  as  the  retort.  It  should  stand  upright,  and  the 
liquor  pump  should  force  the  rich  liquor  through  these 
coils  to  the  top  of  the  retort  or  to  the  heater,  and  the 
poor  liquor  should  pass  in  the  opposite  direction.  In 
causing  the  liquors  to  take  this  course  the  pressure  in  the 
body  of  the  exchanger  can  be  regulated  by  the  valve  on 
the  poor  liquor  pipe  coming  from  the  retort. 

The  amount  of  surface  between  the  poor  and  rich 
liquor  in  exchanger  varies  according  to  its  construction, 
all  the  way  from  twenty-five  to  fifty  square  feet  for  a  10- 
ton  plant  (ice  making  capacity).  This  statement  covers 
those  plants  of  which  we  have  knowledge.  According  to 
Starr,  who  assumes  the  heat  transfer  to  amount  to  40  B. 
T.  units  per  square  foot  surface  per  hour,  for  each  degree 
Fahrenheit  difference  in  temperature,  about  120  square 
feet  of  exchanging  surface  would  be  required  for  an  ice 
making  plant  of  ten  tons  daily  capacity. 

THE  HEATER. 

The  heater  is  another  contrivance  frequently  used  to 
further  the  objects  of  the  exchanger.  It  consists  of  a  coil 


THE  ABSORPTION  SYSTEM.  237 

of  pipe  through  which  the  rich  liquor  passes  from  the 
exchanger  before  it  reaches  the  retort.  This  pipe  is 
located  in  a  drum  in  which  steam  (generally  spent  steam 
from  liquor  pump)  is  circulated.  It  is  constructed  on 
the  same  principles  as  the  other  receptacles  and  coils. 
The  surface  of  the  heater  coil  is  about  thirty  to  fifty 
square  feet  in  a  10-ton  ice  making  plant. 

THE  COOLER. 

The  cooler  is  an  arrangement  frequently  used  to  do 
for  the  poor  liquor  what  the  heater  does  for  the  rich 
liquor,  i.  e.,  to  promote  the  objects  of  the  exchanger  by 
withdrawing  all  the  heat  possible  from  the  poor  liquor 
before  it  reaches  the  absorber.  This  contrivance  is  built 
on  the  same  principles  as  a  condenser,  and  consists  of  a 
coil  or  series  of  coils,  submerged  in  a  tank  through  which 
cooling  water  circulates,  or  placed  over  a  vat  to  allow 
the  cooling  water  to  trickle  over  them,  similar  to  an 
atmospheric  condenser.  The  surface  of  the  cooler  may 
be  from  sixty  to  eighty  feet  for  a  10- ton  ice  making  ma- 
chine, and  larger  or  smaller  for  different  capacities,  as 
the  case  may  be. 

THE  AMMONIA  PUMP. 

The  ammonia  pump,  which  takes  up  the  rich  liquor 
from  absorber  to  force  it  through  the  exchanger  and 
heater  to  the  generator,  is  generally  a  steam  pump,  the  en- 
gine and  pump  cylinder  being  mounted  on  a  common  base. 
A  pump  driven  by  belt  may  also  be  used.  The  size  and 
number  of  strokes  of  pump  depend  on  the  size  of  plant, 
but  also  largely  on  the  strength  of  poor  and  rich  liquor. 
(See  table,  page  139.) 

For  a  10-ton  plant  (ice  making  capacity)  the  pump 
has  generally  a  diameter  of  three  inches,  the  stroke 
being  from  six  to  ten  inches  and  the  number  of  strokes 
from  twenty-five  to  fifty  per  minute.  The  ammonia 
pump  is  generally  single-acting,  in  order  to  relieve  the 
pressure  on  stuffing  box,  which  latter  fixture  requires 
particular  care  in  order  to  secure  proper  working  of  the 
pump. 

MISCELLANEOUS  ATTACHMENTS. 

Like  the  condenser,  the  refrigerator,  expansion  coils, 
as  also  the  brine  tank  (and  brine  pump)  or  the  freez- 
ing tank,  are  constructed  on  the  same  lines  in  an  absorp- 
tion as  in  a  compression  plant,  and  therefore  need  no  fur- 
ther mention  here.  The  same  may  be  said  of  the  expan- 


238  MECHANICAL  REFRIGERATION. 

sion  valve,  and  of  other  valves  required  when  desirable 
to  shut  off  certain  portions  of  the  machine,  of  the  required 
pressure  gauges,  thermometers  and  other  attachments. 
In  the  use  of  the  absorption  plant  for  various  purposes 
the  same  rules  apply  as  in  the  use  of  a  compression  ma- 
chine. As  the  spent  steam  from  the  generator  is  used 
for  distilled  water,  and  as  the  same  cannot  be  contam- 
inated with  lubricating  oil,  the  steam  filter  or  oil  sepa- 
rator is  superfluous  if  the  boiler  feed  water  is  of  ordinary 
purity. 

OVERHAULING  PLANT. 

In  order  to  keep  an  absorption  plant  in  the  best 
possible  order  for  the  longest  possible  time  it  is  neces- 
sary that  the  different  parts  be  opened  and  overhauled 
from  time  to  time  (according  to  the  water  used  and  as 
other  conditions  may  indicate)  every  alternate  season  or 
so  in  order  to  thoroughly  clean  and  inspect  the  interior 
part,  and  to  repair  them  in  order  to  anticipate  any  pos- 
sible breakdowns,  etc.  In  all  cases,  before  starting  up  to 
open  a  new  season,  the  coils  and  traps  should  be  tested. 

COMPRESSION  VERSUS  ABSORPTION. 

The  question  is  frequently  asked  as  to  which  kind  of 
refrigerating  plant— a  compression  or  absorption  plant- 
is  the  most  profitable  and  the  most  economical;  and 
many  different  answers  are  given  to  these  questions.  Dif- 
ferent as  the  two  kinds  of  machines  look  at  first  sight, 
the  theoretical  principles  as  well  as  defects  are  the  same, 
as  has  been  already  explained,  although  the  natural 
facilities,  as  relative  price  of  coal  and  cooling  water,  etc., 
may  be  more  favorable  in  certain  localities  for  one  class 
of  machines  than  for  another.  Taking  this  into  due  con- 
sideration,.  the  principal  difference  between  the  two 
machines  in  a  given  case  must  be  sought  in  the  more  or 
less  greater  care  and  perfection  with  which  they  are 
built  and  operated,  more  particularly  also  in  the  quality, 
quantity  and  proper  distribution  of  material,  the  work- 
manship and  the  life  of  the  plant,  considering  also  the 
kind  of  water  and  ammonia  to  be  used. 

When  it  is  considered  how  difficult  it  is  to  give  due 
regard  to  all  these  circumstances  in  the  valuation  or 
planning  of  an  individual  plant,  the  apparently  conflict- 
ing results  of  different  kinds  of  plants  working  in  differ- 
ent localities  and  conditions,  and  the  different  opinions 
on  them  are  explained  in  a  great  measure. 


THE  ABSORPTION  SYSTEM. 
TABULATED  DIMENSIONS,  ETC. 


239 


The  great  variations  in  the  dimensions  of  the  various 
parts  of  absorption  machines  of  different  makes  find 
expression  in  the  following  table,  which  purports  to  give 
the  dimensions,  capacity,  etc.,  of  different  machines. 
For  the  correctness  of  these  figures  we  are  unable  to 
vouch,  as  the  manner  in  which  we  obtained  them  does  not 
exclude  clerical  errors,  hence  we  must  -submit  them  for 
what  they  are  worth: 


TABLE  SHOWING  DIMENSIONS,   ETC.,   OF  ABSORPTION 
MACHINES. 


Actual    Ice    making 
capacity  in  tons  of 
ice       

3 

8 

12 

15 

25 

10 

Number  and  size  of 
steam  boiler   horse 
power    or    dimen- 
sions   
Pounds  of  coal  used 

15 

65 

30 
140 

40"x20' 
135 

50 
220 

J2    42" 

1  x21l/2' 

504 

12    42" 
fxlO' 
168-180 

Number  and  size  of 

30"xlO' 

30"xl6' 

24"xl8' 

44"xl4' 

J2    30" 

28"xl5' 

Size  of  coil  in  gener- 
ator in  square  feet 
Surf  ace  of  disks,  etc., 
in    analyzer    in 

24 
10 

48 
20 

91 
64 

96 
34 

1  xlllA' 
400 

125 

80 
24 

Cooling    surface    in 
exchanger    in 
square  feet  
Cooling    surface    of 
traps  in  absorber  in 

34 
130 

51 
260 

22* 
191 

68 
470 

65 
1900 

25 
673 

Cooling    surface     in 
condenser  in  square 
f  eet              

345 

690 

220 

1380 

1220 

544 

Surface  in  expander 
or   refrigerator   in 
square  feet  
Cooling    surface     in 
rectifier  in  square 

f  QQ^i                                      

410 

1200 

726 
25 

2100 

4000 

1600 

Cooling    surface    in 

41 

Temperature    of 
water  in  degrees  F. 
Temperature    of 
brine  in  degrees  F. 

70 
10-20 

70 
10-20 

80 
10-12 

70 
10-20 

76 

7 

80-94 
10-14 

From  the  foregoing  table  it  appears  that  in  absorp- 
tion machine  one  pound  of  coal  will  make  from  four  to 
seven  pounds  of  ice.  On  the  continent  it  is  assumed  that 
one  pound  of  coal  will  make  about  ten  pounds  of  ice  in 
an  absorption  machine ;  the  evaporative  power  of  the 
coal  being  taken  at  eight  pounds  of  water  per  pound  of 


240  MECHANICAL  REFRIGERATION. 

CHAPTER  X.— THE  CARBONIC  ACID  MACHINE. 

GENERAL  CONSIDERATIONS. 

Among  the  refrigerating  machines  which  use  other 
refrigerating  media  than  ammonia,  those  compression 
machines  using  carbonic  acid  have  found  favor  for  many 
specific  purposes,  especially  so  for  the  refrigeration  of 
storage  rooms  in  hotels  and  restaurants,  where  the  im- 
peccability of  the  gas  to  victuals  is  prominently  valued. 
The  non-corroding  action  of  carbonic  acid  on  any  of  the 
metals,  and  the  fact  that  it  cannot  be  decomposed  dur- 
ing compression,  etc.,  speak  principally  in  favor  of  its 
use.  The  fact  that  a  leak  of  carbonic  acid  is  not  demon- 
strated by  its  smell  might  be  overcome  by  the  addition 
of  some  odoriferous  substance.  The  capacity  of  the 
compressor  may  be  very  small  as  compared  with  other 
refrigerating  plants  (see  page  89),  but  the  parts  of  the 
machine  must  also  be  made  correspondingly  stronger  on 
account  of  the  high  pressure  of  the  gas. 

The  cheapness  of  liquefied  carbonic  acid  is  also  quoted 
in  its  favor  as  a  refrigerating  agent,  as  also  its  lesser  dan- 
ger to  respiration  in  case  of  leaks.  It  is  claimed  that  air 
containing  8  per  cent  of  carbonic  acid  gas  can  be  inhaled 
without  danger,  while  an  atmosphere  containing  only  K 
per  cent  of  ammonia  is  said  to  be  decidedly  dangerous. 
On  the  other  hand,  the  presence  of  the  least  amount  of 
ammonia  in  the  air  demonstrates  itself  by  the  smell, 
while  this  is  not  the  case  with  carbonic  acid. 

Not  only  the  neutrality  of  carbonic  acid  toward 
metals  and  packings,  but  also  toward  water,  meat,  beer 
and  other  products  subjected  to  cold  storage,  should  be 
mentioned  in  this  connection. 

The  use  of  carbonic  acid  in  refrigerating  machines 
of  the  compression  type  has  been  somewhat  stimulated 
by  the  cheap  manufacture  of  liquid  carbonic  acid  as  a 
by-product  of  the  brewing  industry,  especially  in  Ger- 
many, where  over  400  such  machines  (1894)  are  said  to  be 
working  satisfactorily. 

PROPERTIES  OF  CARBONIC  ACID. 

The  carbonic  acid,  which  is  a  gas  of  1.529  specific 
gravity  (air  =  1)  at  the  atmospheric  pressure,  becomes 
liquid  at  a  temperature  of  —124°  F.  at  that  pressure.  At 
32°  F.  it  is  liquid  under  a  pressure  of  36  atmospheres,  and 
then  has  a  specific  weight  of  0.93  (water=  1).  The  specific 
weight  of  the  liquid  at  different  temperatures,  according 


THE  CAT5BONIC  ACID  MACHINE. 


241 


to  Mitchel,  is  at  32°  F.  =  0.93,  at  42°  F.  =  0.8825,  at 
47.30  F.,=  o.853,  at  65.3°  F.=  0.7385,  and  at  86°  F.=0.60. 

The  specific  heat  of  carbonic  acid  gas  by  weight 
=  0.2167  (air  =  0.2375).  Of  the  liquid  it  is  1 .  . 

The  author's  attention  has  been  called  to  the  appar- 
ent inconsistency  existing  between  the  specific  gravity 
of  liquid  carbonic  acid,  as  given  in  the  foregoing  para- 
graph (0.6  at  86°  F.),  and  the  amount  of  carbonic  acid 
contained  in  the  cylinders  in  which  the  same  is  shipped. 
The  cylinders  have  a  capacity  of  805  cubic  inches  (29.11 
pounds  of  water)  and  are  made  to  contain  20  pounds  of 
liquid  carbonic  acid,  and  some  manufacturers  are  said  to 
crowd  in  21  and  22  pounds,  although  this  is  doubtless  a 
very  risky  proceeding.  But  even  at  20  pounds  the  cyl- 
inders contain  over  2>£  pounds  more  (at  86°  F.)  than 
what  is  consistent  with  the  above  specific  gravity.  The 
fact  that  the  drums  do  not  burst  with  such  a  charge 
tends  to  show  that  the  foregoing  specific  gravity  is  not 
correct  (too  low)  or  that  different  densities  exist  for 
different  pressures  at  or  near  the  temperatures  charac- 
terizing the  critical  condition  of  carbonic  acid  (88°  F.)- 

PROPERTIES  OF  SATURATED  CARBONIC  ACID  GAS. 

Transformed  to  English  units  from  a  metric  table  computed  by 
Prof.  Schroter,  by  Denton  and  Jacobus. 


Tem- 
pera- 
ture of 
ebulli- 
tion in 
deg.  F. 

Abso- 
lute 
press- 
ure in 
Ibs.  per 
sq.  in. 

Total 
heat 
reck'n'd 
from  32° 
Fahr. 

Heat  of 
liquid 
reck'n'd 
from  32° 
Fahr. 

Latent 
heat  of 
evapo- 
ration. 

Heat 
equiv- 
alent 
of  ex- 
ternal 
work. 

Incr'se 
of  vol- 
ume 
during 
evapo- 
ration. 

Dens'  y 
of  va- 
por or 
weight 
of  one 
cu.  ft. 

t 

P-M44 

y 

q 

r 

APit 

u 

—22 

210 

98.35 

—37.80 

136.15 

16.20 

.4138 

2.321 

-13 

249 

99.14 

—32.51 

131.65 

16.04 

.3459 

2.759 

-  4 

292 

99.88 

—26.91 

126.79 

15.80 

.2901 

3.265 

5 

342 

100.58 

-20.92 

121.50 

15.50 

2438 

3.853 

14 

396 

101.21 

—14.49 

115.70 

15.08 

.2042 

4.535 

23 

457 

101.81 

—  7.56 

109.37 

14.58 

.1711 

5.331 

32 

525 

102.35 

0.00 

102.35 

13.93 

.1426 

6.265 

41 

599 

102.84 

8.32 

94.52 

13.14 

.1177 

7.374 

50 

680 

103.24 

17.60 

85.64 

12.15 

.0960 

8.708 

59 

768 

103.59 

28.22 

75.37 

10.91 

.0763 

10.356 

68 

864 

103.84 

40.86 

62.98 

9.29 

.0577 

12.480 

77 

968 

103.95 

57.06 

46.89 

7.06 

.0391 

15.475 

86 

1,080 

103.72 

84.44 

19.28 

2.95 

.0147 

21.519 

A,  in  the  column  heading,  stands  for  the  reciprocal  of  the  mech- 
anical equivalent  of  heat. 

The  preceding  table,  showing  the  properties  of  satur- 
ated carbonic  acid,  may  be  used  in  connection  with  the 
formulae  given  in  the  chapter  on  the  ammonia  compres- 


242  MECHANICAL  REFRIGERATION. 

sion  system.  However,  the  results  obtained  in  this  man- 
ner are  only  approximations,  since  the  carbonic  acid  is  in 
a  superheated  condition  during  several  stages  of  the  cycle 
constituting  the  refrigerating  process,  as  a  reference  to 
the  practical  data,  given  hereafter,  will  amply  show. 

CONSTRUCTION  OF  PLANT. 

The  refrigerating  plants  operated  with  carbonic  acid 
are  built  on  the  same  general  plan  as  the  ammonia  com- 
pression plants,  compressor,  condenser  and  refrigerator 
being  the  identical  important  parts,  specified  as  follows 
by  a  leading  manufacturer: 

THE  COMPRESSOR. 

The  compressor  is  either  of  the  horizontal  or  the  ver- 
tical type  (for  smaller  machines  generally  the  latter).  It 
should  be  made  of  the  best  material,  steel  or  semi-steel, 
and  it  is  provided  with  a  jacket  through  which  the  return 
gas  passes,  which  arrangement  gives  additional  strength 
to  the  cylinder  and  tends  to  keep  it  cool.  The  piston 
rods,  connecting  rods,  crank  pins  and  valves  should  be 
made  of  forged  steel,  and  so  as  to  be  interchangeable  at 
any  time. 

STUFFING  BOX. 

The  stuffing  box  is  made  gas  tight  by  means  of  cupped 
leathers  on  the  compressor  rod.  Glycerine  is  forced  into 
the  spaces  between  these  leathers  at  a  pressure  superior 
to  the  suction  pressure  in  the  compressor,  so  that  what- 
ever leakage  takes  place  at  the  stuffing  box  is  a  leakage 
of  glycerine  either  into  the  compressor  or  out  into  the 
atmosphere,  and  not  a  leakage  of  gas. 

What  little  leakage  of  glycerine  takes  place  into  the 
compressor  is  advantageous,  inasmuch  as  it  in  the  first 
place  lubricates  the  compressor,  and  in  the  second  place 
fills  up  all  clearances,  thereby  increasing  the  efficiency  of 
the  compressor. 

In  order  to  replace  the  glycerine  which  leaks  out  of 
the  stuffing  box  of  the  horizontal  machine,  there  is  a  belt 
driven  pump  which  operates  continuously.  The  smaller 
machines  are  fitted  with  a  hand  pump,  a  few  strokes  of 
which  are  required  to  be  made  every  four  or  five  hours. 

GLYCERINE    TRAP. 

Any  glycerine  which  passes  into  the  compressor  be- 
yond what  is  necessary  to  fill  the  clearance  spaces  is  dis- 
charged with  the  gas  through  the  delivery  valves.  In 
order  to  prevent  this  going  into  the  system,  all  the  liquid 


THE  CAHBONIC  ACID  MACHINE.  243 

passes  through  a  trap  in  which  the  glycerine  drains  to  the 
bottom,  whence  it  is  drawn  off  from  time  to  time. 

It  may  be  remarked  here  that  the  glycerine  has  no 
affinity  for  carbonic  anhydride,  hence  it  undergoes  no 
change  in  the  machine,  and  therefore  there  is  no  chance 
of  the  condenser  coils  becoming  clogged. 

CONDENSER. 

The  condenser  consists  of  coils  of  wrought  iron  extra 
heavy  pipes,  which  are  either  placed  in  a  tank  and  sur- 
rounded by  water,  or  are  so  arranged  that  water  trickles 
over  them,  forming  the  well  known  atmospheric  con- 
denser. The  coils  are  welded  together  into  such  length 
as  to  avoid  any  joints  inside  the  tank,  where  they  would 
be  inaccessible. 

In  connection  with  the  condensers,  where  sea  water 
only  is  available  for  condensing  purposes,  one  very  im- 
portant advantage  of  carbonic  anhydride  machines  is 
claimed:  As  carbonic  anhydride  has  no  chemical  action 
on  copper,  this  metal  is  used  in  the  construction  of  the 
coils,  giving  same  longer  life. 

EVAPORATOR. 

The  evaporator  consists  of  coils  of  wrought  iron  extra 
heavy  pipe,  welded  into  long  lengths,  inside  which  the 
carbonic  anhydride  evaporates.  The  heat  required  for 
evaporation  is  usually  obtained  either  from  brine  sur- 
rounding the  pipes,  as  in  cases  where  brine  is  used  as  the 
cooling  medium,  or  else  from  air  surrounding  the  pipes, 
as  in  cases  where  air  is  required  to  be  cooled  direct. 

Between  the  condenser  and  evaporator  there  is  a 
regulating  or  so  called  expansion  valve  for  adjusting  the 
quantity  of  the  liquid  carbonic  anhydride  passing  from 
the  condenser. 

SAFETY  VALVE. 

In  order  to  enable  the  compressor  to  be  opened  up  for 
examination  of  valves  and  piston  without  loss  of  carbonic 
anhydride,  it  is  necessary  to  fit  a  stop  valve  on  the  suction 
and  delivery  sides  so  as  to  confine  the  carbonic  anhydride 
to  the  condenser  and  evaporator.  It  is,  of  course,  pos- 
sible for  a  careless  attendant  to  start  the  machine  again 
without  opening  the  delivery  valve,  and  in  such  cases  an 
excessive  pressure  would  be  created  in  the  delivery  pipe, 
from  which  there  would  be  no  outlet.  To  provide  aga  inst 
this  danger  a  safety  device  is  adopted,  consisting  of  a 
housing,  at  the  base  of  which  is  a  thin  disk,  which  is 


244  MECHANICAL  REFRIGERATION. 

designed  to  blow  off  at  a  pressure  considerably  below 
that  to  which  the  machines  are  tested. 

JOINTS. 

All  joints  should  be  made  with  special  flange  unions 
and  brass  bushings.  They  should  be  made  absolutely 
tight  with  packing  rings  of  vulcanized  fiber,  which  with- 
stand the  heat  and  still  have  the  necessary  elasticity  to 
insure  the  joint  being  perfectly  tight  when  either  hot 
or  cold. 

STRENGTH  AND  SAFETY. 

The  working  pressure  varies  from  about  fifty  to 
seventy  atmospheres.  Owing  to  the  very  small  diameter 
of  all  parts,  even  in  large  machines,  there  is  no  difficulty 
in  securing  a  very  ample  margin  of  strength.  All  parts 
of  the  machine  subject  to  the  pressure  of  the  carbonic 
anhydride  should  be  tested  at  three  times  the  working 
pressure. 

APPLICATION  OF  MACHINE. 

Both  the  direct  expansion  and  the  brine  system  are 
used  in  connection^  with  a  carbonic  acid  refrigerating 
machine,  but  for  most  purposes  the  former  is  deemed 
preferable,  as  is  also  the  case  with  ammonia  compression. 
For  ice  making  the  can  or  plate  system  may  be  used,  and 
also  for  other  refrigerating  purposes  the  application  of 
the  carbonic  acid  refrigerating  plant  is  quite  similar  to 
that  of  any  other  compression  or  absorption  plant.  A 
plant  quite  similar,  or  rather  identical  in  its  main  feature 
with  a  carbonic  acid  refrigerating  plant  is  also  used  for 
the  manufacture  of  liquefied  carbonic  acid,  as  it  may  be 
obtained  from  breweries,  distilleries,  calcination  of  lime 
and  other  sources. 

EFFICIENCY  OF  SYSTEM. 

The  efficiency  of  the  carbonic  acid  machine  is  some- 
what lessened  by  the  high  specific  heat  of  the  liquid, 
and  therefore  decreases  with  greater  divergence  of  tem- 
perature. It  has  been  proposed  to  reduce  this  loss  in 
efficiency  by  introducing  a  motor  between  the  condenser 
and  refrigerator,  which  would  perfect  the  cycle  of  opera- 
tions. After  another  method,  the  loss  of  efficiency  due 
to  the  specific  heat  of  liquid  is  reduced  by  allowing  the 
liquid  during  its  flow  to  expand  from  the  condenser 
pressure  to  an  intermediate  pressure,  and  to  return  the 
vapors  so  produced  after  having  cooled  the  remaining 
liquid  to  tie  condenser  by  an  auxiliary  compressor, 


THE  CARBONIC  ACID   MACHINE.  245 

It  has  frequently  been  argued  that  carbonic  acid 
compression  machines  could  not  be  operated  successfully 
when  the  temperature  of  the  condenser  water  exceeds 
88°  F.,  the  critical  temperature  of  carbonic  acid.  Accord- 
ing to  the  present  conception  of  the  critical  condition, 
above  the  said  temperature  carbonic  acid  can  only  exist 
in  the  gaseous  form,  and  cannot  be  converted  into  a 
liquid  by  means  of  the  withdrawal  of  the  latent  heat 
of  volatilization.  This  being  the  case,  the  refriger- 
ating effect  of  a  carbonic  acid  machine  working  with 
condenser  water  above  88°  F.  would  only  be  that  of  a 
compressed  gas  while  expanding  against  resistance, 
which  would  be  comparatively  small  when  compared  with 
refrigerating  effect  produced  by  the  volatilization  of 
the  liquefied  medium.  These  considerations  and  argu- 
ments are,  however,  in  direct  conflict  with  the  statements 
of  Windhausen,  according  to  which  carbonic  acid  ma- 
chines operated  with  condensing  water  of  90°  to  94°  F. 
and  in  tropical  countries  produce  refrigerating  effects 
ten  times  larger  than  what  they  would  be  if  the  carbonic 
acid  acted  simply  as  a  compressed  gas  at  such  tempera- 
tures. 

Experiments  cited  by  Linde  show  that  a  carbonic 
acid  machine  working  with  a  temperature  of  92°  F.  at 
the  expansion  valve  gives  a  refrigerating  effect  about  50 
per  cent  less  than  when  the  temperature  at  the  expan- 
sion valve  was  53°  F. 

CAUSE  OF  APPARENT  INCONSISTENCIES. 

The  foregoing  and  other  apparent  inconsistencies  be- 
tween the  theory  and  practice  of  the  working  of  the  car- 
bonic acid  refrigerating  plant  have  recently  been  fully  ex- 
plained on  the  basis  that  the  carbonic  acid  is  in  the  state 
of  a  superheated  gas  in  the  compression  stage;  in  fact, 
it  must  be  so  if  the  condensing  gas  reaches  a  tempera- 
ture over  80°,  in  order  to  produce  refrigerating  effects  at 
all.  The  loss  due  to  the  absence  of  an  expansion  cylinder 
(completing  a  perfect  reversible  cycle)  to  reduce  the  tem- 
perature of  the  liquefied  carbonic  anhydride  from  the 
temperature  of  the  condenser  to  that  of  the  refrigerator, 
which  constitutes  the  chief  difference  in  the  economy 
between  ammonia  and  carbonic  acid  refrigerating  ma- 
chines, has  ajso  been  somewhat  overestimated  in  dero- 
gation of  the  carbonic  acid  machine  as  shown  by  Mollier 


246 


MECHANICAL  REFRIGERATION. 


COMPARISONS  OF  EFFICIENCY. 

The  calculation  on  the  former  basis  (specific  heat 
times  weight  of  ciirbonic  acid  circulated  is  unit  of  time) 
gave  this  loss  as  about  0.80  per  cent  of  the  whole  theoretical 
refrigerating  effect  for  every  degree  difference  between 
the  temperature  of  the  condenser  and  that  of  the  refrig- 
erator, as  compared  with  0.18  per  cent  loss  in  the  case  of 
ammonia.  The  accompanying  table  was  calculated  and 
published  by  Ewing  several  months  ago,  showing  the 
relation  between  the  ammonia  and  carbonic  acid  refrig- 
erating plant  with  reference  to  the  loss  due  to  cooling  of 
the  liquid.  In  this  table  the  upper  limit  of  temperature 
in  the  condenser,  or  rather  immediately  before  the  ex- 
pansion valve,  is  taken  at  68°  F.,  while  the  temperature 
in  the  refrigerator  varies  from  50°  to  — 4°  F. 

THEORETICAL  CO-EFFICIENT  OF  PERFORMANCE  IN  VA- 
POR COMPRESSION  MACHINES,  UNDER  WET  COMPRES- 
SION, UPPER  LIMIT  OF  TEMPERATURE  BEING  68°  F. 


Lower  Limit 
of 
Temperature, 
Deg.  F. 

Theoretical  Co-efficient  of 
Performance. 

Co-efficient  of 
Performance 
in 
Oarnot  Cycle. 

Ammonia. 

Carbonic  Acid. 

50 

40 
32 
33 
14 

—4 

27.8 
18.1 
13.2 
10.2 
8.3 
6.9 

25.7 
20. 
11.4 

8.5 
6.8 
4.5 

28.3 
18.5 
13.6 
10.7 
8.8 
6.3 

It  will  be  noticed  that  with  ammonia  the  theoretical 
performance— namely,  that  of  a  compression  machine 
without  an  expansion  cylinder— is  only  a  little  less  than 
the  ideal  performance  which  would  be  obtained  by  fol- 
lowing Carnot's  cycle.  Hence  with  this  substance  al- 
most nothing  would  be  gained  by  adding  an  expansion 
cylinder  to  the  machine— nothing,  certainly,  that  would 
in  any  way  compensate  for  the  increase  of  complexity 
and  friction  and  cost  which  an  expansion  cylinder  would 
involve. 

With  carbonic  acid  there  is  considerably  more  falling 
away  from  the  ideal  of  Carnot,  for  the  reason  that  the 
specific  neat  of  the  liquid  bears  a  greater  proportion  to 
the  latent  heat  of  the.  vapor.  But  even  then  the  saving 
in  work  which  an  expansion  cylinder  would  bring  about 
is  not  great,  and  in  practice  the  expansion  cylinder,  even 
in  carbonic  acid  machines,  is  never  used  so  far. 


THE  CARBONIC  ACID  MACHINE. 


24" 


PRACTICAL  COMPARATIVE  TESTS. 

Quite  a  number  of  practical  tests  published  by  Linde 
several  years  ago  led  him  to  the  compilation  of  the  fol- 
lowing table,  which  shows  the  excess  of  efficiency  in  per 
cents  of  ammonia  refrigerating  machine  over  and  above 
that  of  a  carbonic  acid  machine,  both  working  'at  differ- 
ent temperatures  before  the  expansion  valve,  the  temper- 
ature in  the  brine  surrounding  expansion  coil  being  the 
same  (about  23°  F.)  in  all  cases. 


Temperature  before  expan- 
sion valve  °  F  

54° 

63° 

72° 

81° 

90° 

Excess  of  efficiency  of  am- 
monia plant  

17  '% 

2356 

3156 

47J6 

101J6 

The  tests  referred  to  by  Linde,  on  which  the  fore- 
going table  is  based,  were  made  in  the  Experimental 
Refrigerating  Station  in  Munich,  Germany,  by  Schroeter, 
and  in  the  following  little  table  are  compiled  some  of  the 
actual  results  of  these  experiments  obtained  in  the  case 
of  an  ammonia  and  of  a  carbonic  acid  refrigerating  ma- 
chine: 


AMMONIA  MACHINE. 

CARBONIC  ACID 
MACHINE. 

No.  OF  TEST. 

1 

2 

3 

4 

5 

6 

7 

8 

Temp,  in  brine  tank, 

degrees  Celsius.  .. 

—6.1 

-6.4 

—6.4 

-4.8 

—4. 

—4.8 

—4.8 

—6.7 

Temp,  in  condenser, 
degrees  Celsius  .  .  . 

21.4 

21.4 

21.4 

34.9 

20.9 

21.2 

22.2 

30 

Temp,  before  expan- 
sion valve,  degrees 

Celsius  

—6.5 

11.6 

18.4 

28.3 

—7.9 

10 

16.8 

28.8 

Refrigeration  per 
hour  per   horse 

power  of  steam  en 
gine  in  calories  .  .  . 

3,897 

3,636 

3,508 

2,237 

3,832 

3,178 

2,867 

1,477 

The  correctness  of  these  figures  has  never  been 
doubted,  and  in  view  of  these  facts  the  efficiency  of  a 
carbonic  acid  machine  now  in  the  market,  which  is  given 
at  4,300  and  3,700  calories  for  temperatures  of  10°  and  20° 
Celsius  before  the  expansion  valve  per  indicated  horse 
power,  must  be  considered  as  something  phenomenal 
indeed.  This  machine  has  no  expansion  cylinder,  and 
therefore  its  efficiency  is  comparable  to  the  efficiencies 
given  under  tests  6  and  7  in  the  above  table,  which 
are  nearly  25  per  cent  less. 


243  MECHANICAL  REFRIGERATION'. 

CHAPTEK  XI.-OTHER  COMPRESSION  SYSTEMS. 

AVAILABLE  REFRIGERATING  FLUIDS. 

Besides  ammonia  other  liquids  are  used,  and  still 
others  have  been  proposed  as  working  fluids  in  refriger- 
ating machines.  Most  of  these  liquids  are  used  on  the 
same  plan  as  ammonia  in  the  compression  system,  and 
the  machines,  barring  certain  details,  are  constructed 
on  the  same  principles  as  the  ammonia  compression  ma- 
chine, and  the  same  rules  and  calculations  apply  to  all 
of  them.  The  following  table  shows  the  pressure  and 
boiling  point  of  some  liquids  available  for  use  in  refriger- 
ating machines  as  given  by  Ledoux.  (Denton  and 
Jacobus'  edition.) 


Tension  of  Vapor,  in  pounds  per  square  inch,  above 
Zero. 


Deg. 
Fahr. 

Sul- 
phuric 
ether. 

Sul- 
phur di- 
oxide. 

Am- 
monia 

Methy- 
lic 
ether. 

Car- 
bonic 
acid. 

Pictet 
fluid. 

(1) 

(2) 

(3) 

(4) 

(5) 

(6) 

(7) 

—40 

10.22 

—31 

13.23 

—  22 

5  56 

16  95 

11  15 

—13 

7  23 

21.51 

13  85 

251  6 

—  4 

1.30 

9.27 

27.04 

17.06 

292.9 

J3.5 

5 

1.70 

11.76 

33.67 

20.84 

340.1 

16.2 

14 

2.19 

14.75 

41.58 

25.27 

393.4 

19.3 

23 

2.79 

18.31 

50.91 

30.41 

453.4 

22.9 

32 

3.55 

22.63 

61.86 

3(5.34 

520.4 

26.9 

41 

4.45 

27.48 

74.55 

43.13 

694.8 

31.2 

50 

5.54 

33.26 

89.21 

50.84 

676.9 

36.2 

59 

6.84 

39.93 

105.99 

59.56 

766.9 

41.7 

68 

8.38* 

47,62 

125.08 

69.35 

864.9 

48.1 

77 

10.19 

56.39 

146.64 

80.28 

971.1 

55.6 

86 

12.31 

66.37 

170.83 

92.41 

1,085.6 

64.1 

95 

14  76 

77  64 

197.  83 

1,207.9 

73  2 

104 

17  59 

90  32 

227.76 

1,338.2 

82.9 

MACHINES  IN  ACTUAL  OPERATION. 

Of  those  compression  machines  which  are  in  actual 
usfe  besides  the  ammonia  and  carbonic  acid  machine, 
which  have  been  described  already,  those  operated  with 
sulphur  dioxide,  Pictet  liquid,  ethylic  ether  (sulphuric 
ether),  ethyl  chloride  and  methyl  chloride  may  be  men- 
tioned especially.  The  latter  machine  is  comparatively 
new,  and  not  so  far  in  practical  use  to  any  extent,  and 
therefore  no  special  account  can  be  given  of  the  same 
in  the  following  short  remarks. 


OTHER  COMPRESSION  SYSTEMS.  240 

Recently  we  have  found  some  accounts  given  of  a 
machine  operated  with  chloride  of  methyl  in  an  ice  fac- 
tory at  Algiers.  We  are  informed  that  the  size  of  the 
engine  is  30  horse  power,  that  about  eighty  pounds  of 
the  chemical  at  about  fifty  cents  per  pound  were  needed 
to  operate  the  plant  during  5,000  hours  without  the  least 
disturbance,  and  we  are  informed  of  a  number  of  other 
details,  but  as  to  the  actual  amount  of  ice  produced  we 
are  left  in  the  dark  entirely.  The  temperature  of  the 
brine  is  —  4°F.  The  pressure  in  the  expander  appears  to 
be  very  low 

THE  ETHYL  CHLORIDE  MACHINE. 

A  refrigerating  machine  using  ethyl  chloride  as  a 
refrigerant  has  been  in  use  to  some  extent  lately.  The 
ethyl  chloride  evaporates  at  a  quite  high  temperature; 
the  machine  works  under  a  vacuum,  and  condensing 
pressures  are  very  low,  about  fifteen  pounds  (gauge 
pressure)  as  a  maximum.  The  refrigerating  coils  are 
made  of  sheet  copper,  flat,  several  inches  broad,  and 
about  an  inch  thick  in  an  experimental  plant  in  opera- 
tion in  Chicago.  The  machine  appears  to  be  designed 
for  small  work  only,  fruit  rooms,  creameries,  small 
butcher  shops,  etc.,  and  is  operated  by  any  sort  of  a 
small  motor. 

REFRIGERATION  BY  SULPHUR  DIOXIDE. 

The  sulphurous  acid  refrigerating  machines  are  also 
in  practical  operation  to  some  extent.  They  require,  how- 
ever, a  much  greater  compressor  capacity  than  the  am- 
monia compressors  (nearly  three  times  as  much),  and  give 
a  low  efficiency  at  very  low  refrigerator  temperatures. 

PROPERTIES  OF  SULPHURIC  DIOXIDE. 

The  specific  heat^of  liquid  sulphurous  acid  is  0.41; 
the  critical  pressure  79  atmospheres,  and  the  critical 
temperature  312°  F.  The  specific  gravity  of  the  gaseous 
acid  is  2.211  (air  =  l),  and  the  specific  gravity  of  the 
liquid  at-  4^  F  =  1.491. 

The  relation  of  the  specific  gravity,  s,  of  the  liquid 
to  the  temperature,  t,  is  expressed  by  the  following  for- 
mula given  by  Andreef: 

s  =  1.4333  —  0.00277  t  —  0.000000  271 1* 

The  specific  heat  of  liquid  sulphurous  acid  is  0.4J 
(water  — 1). 


250  MECHANICAL  REFRIGERATION. 

LEDOUX'S  TABLE  FOR  SATURATED  SULPHUR  DIOXIDE  GA3 


§1 

p! 

ha 

°3g 
f|| 

»2o3  . 

•°£:2.s 

otal  Heat 
Rec  k  o  n  e  d 
from  32°  F. 

1 

atent  Heat 
of  Evapora- 
tion. 

!eat  Equiva- 
lent of  Ex- 
ternal Work 

a  crease  of 
Volume  dur- 
ing Evapor 
ation. 

_ 

°°J;| 

H 

<J 

fc-i 

n 

ij) 

n 

i—  i 

Q 

t 

P-^-144 

A. 

Q 

r 

APu 

u 

Deg.    Fan. 

Lbs. 

B.T.U. 

B.T.U. 

B.T.U. 

B.T.U. 

Cub.  Ft. 

Lbs. 

—22 

5.56 

157.43 

—19.66 

176.99 

13.59 

13.17 

.076 

-13 

7.23 

158.64 

-16.30 

174.95 

13.83 

10.27 

.097 

9.27 

159.84 

—13.05 

172.89 

14.05 

8.12 

.123 

~5 

11.76 

161.03 

—  9.79 

170.82 

14.26 

6.50 

.153 

14 

14.74 

162.  20 

—  6.53 

168.73 

14.46 

5.25 

.190 

23 

18.31 

163.36 

—  3.27 

166.63 

14.66 

4.29 

.232 

32 

22.63 

164.61 

0.00 

164.61 

14.84 

3.54 

.282 

41 

27.48 

165.65 

3.27 

162.38 

15.01 

2.93 

.340 

50 

33.25 

166.78 

6.55 

160.23 

15.17 

2.45 

.407 

59 

39.93 

167.90 

9.83 

158.07 

15.32 

2.07 

.483 

68 

47.61 

168.99 

13.11 

155.89 

15.46 

1.75 

.570 

77 

56.39 

170.09 

16.39 

153.70 

15.59 

1.49 

.669 

86 

66.36 

171.17 

19.69 

151.49 

15.71 

1.27 

.780 

95 

77.64 

172.24 

22.98 

149.26 

15.82 

1.09 

.906 

104 

90.31 

178.30 

26.28 

147.02 

15.91 

.91 

1.046 

USEFUL  EFFICIENCY. 

Exceptional  care  has  to  be  taken  to  maintain  tight 
joints  in  a  sulphur  dioxide  machine,  as  any  leakage 
might  produce  sulphuric  acid,  which  would  become  de- 
structive to  the  metal  of  the  plant. 


Temp,  in  degrees 
Fahr.correspond- 
ing  to  pressure  of 
vapor. 

Ice  melting  capacity  per  pound 
of  coal,  assuming  three  pounds  per 
hour  per  horse-power. 

No. 

of 

Test. 

Theoreti- 

Per cent  loss 

Con- 
denser. 

Suction. 

cal  fric- 
tion* in- 

Actual. 

due  to  cylin- 
der super- 

cluded. 

heating. 

ilf 

111 
12 

77.3 

76.2 

28.5 
14.4 

41.3 
31.2 

33.1 
24.1 

19.9 

22.8 

"Q.  O  " 

13 

75.2 

—2.5 

23.0 

17.6 

23.9 

a5| 

80.6 

—15.9 

16.  C 

10.1 

39.2 

.i 

1 

72.3 

26.6 

60.4 

40.6 

19.4 

rf     O 

2 

70.5 

14.3 

37.6 

"30.0 

20.2 

42        tH 

3 

69.2 

0.5 

29.4 

22.0 

25.2 

11 

>* 

68.6 

—11.8 

22.8 

16.1 

29.4 

i  fl 

24 

84.2 

15.0 

27.4 

24.2 

11.  T 

<j  3 

26 

82.7 

—3.2 

21.6 

17.5 

19.0 

1 

26 

84.6 

—10.8 

18.8 

14.5 

22.9 

*Friction  taken  at  figures  observed  in  the  tests  which  range 
from  14  to  20  per  cent  of  the  work  of  the  steam  cylinder. 


OTHER  COMPRESSION  SYSTEMS.  251 

For  a  comparison  of  the  sulphur  dioxide  and  the 
ammonia  compression  plants  the  foregoing  table,  ab- 
stracted from  Schroeter  and  Denton's  tests,  may  be 
cor  suited. 

ETHER  MACHINES. 

Compression  machines,  with  sulphuric  ether  as  the 
working  fluid,  were  in  great  favor  in  former  days,  but 
have  been  abandoned  to  a  great  extent,  owing,  probably, 
to  the  enormous  size  of  compressor  required,  it  being  re- 
quired to  be  about  seventeen  times  as  large  as  an  am- 
monia compressor  of  the  same  capacity.  The  great  in- 
flammability of  the  ether  is  another  objection.  The  for- 
mula and  rules  given  for  the  ammonia  compressor  apply 
also  for  ether,  with  the  exception  that  the  specific  heat 
of  the  saturated  vapor  of  ether  (unlike  that  of  ammonia, 
steam,  carbonic  acid  and  sulphur  dioxide),  is  positive, 
and  therefore  superheats  during  expansion  and  condenses 
during  compression.  An  ether  machine,  therefore,  needs 
no  protection  against  superheating,  and  is  always  oper- 
ated with  dry  vapor.  Specific  heat  of  liquid,  0.51. 


TABLE  SHOWING  PROPERTIES  OF  SATURATED  VAPOR  OF 
ETHER. 


1 

a  £ 

1. 

t 

0,  p 

>d 

e3  i 

>  * 

o 

•23« 

II 

fit* 

J  1302  0 

T3 

p 

1 

>§ 
°1 

3-S 

03  O 

1*11 

1P& 

+J43_a)^ 

<O  Q) 

P> 

of 

S§ 

I 

WS  . 

1 

£  ^ 

ffi 

•" 

W 

E~ 

W~  . 

00 

£ 

B.  T. 

B.  T. 

B.  T. 

B.  T. 

B.  T. 

Units. 

Units. 

Units. 

Units. 

U  nits. 

32 

3.54 

0.00 

376  00 

376.00 

345.80 

30.20 

1.278 

.048 

60 

5.51 

21.28 

393.76 

372.48 

341.48 

31.00 

0.844 

.073 

68 

8.31 

42.80 

411.12 

368.32 

336.52 

31.80 

0.574 

.107 

86 

12.20 

64.56 

428.00 

363.44 

330.88 

32.u6 

0.401 

.154 

104 

17.46 

86.42 

444.44 

357.92 

324.60 

33.32 

0.287 

.232 

122 

24.32 

88.76 

460.44 

351.68 

317  64 

34.04 

0.210 

.294 

140 

33  17 

131.20 

476.00 

344.80 

310.12 

34.68 

0.158 

.392 

158 

44.32 

153.92 

491.12 

337.20 

301.96 

35.24 

0.120 

.515 

176 

58.13 

176.  84 

505.76 

328.92 

293.28 

35.64 

0.093 

.705 

194 

74.96 

200.00 

520.00 

320.00 

284  12 

35.68 

0.073 

.848 

212 

95.25 

223  44 

532.76 

310.32 

274.48 

35.84 

0.057 

1.074 

230 

119.51 

247,08 

547.12 

300.04 

264.52 

35.32 

0.005 

1.350 

248 

148.44 

270.96 

560.00 

289.04 

254.28 

34.76 

0.036 

1.703 

EFFICIENCY  OF  ETHER  MACHINES. 

The  following  data  relating  to  the  working  of  an  ether 
machine  are  not  the  result  of  a  careful  test,  but  repre- 
sent practical  working,  it  is  claimed. 


252 


MECHANICAL  REFRIGERATION. 


For  a  production  of  fifteen  tons  of  ice  in  twenty-four 
hours  245,000  B.  T.  units  were  abstracted  per  hour,  and 
the  indicated  horse  power  of  the  engine  was  eighty-three, 
of  which  forty-six  indicated  horse  power  was  used  for 
the  ether  compressor  and  the  balance  for  friction  in 
compressor,  pumping  water,  working  cranes,  etc.  The 
temperature  of  the  cooling  water  entering  the  condenser 
was  52°  F.  in  this  case. 

REFRIGERATION  BY  PICTET'S  LIQUID. 

This  liquid,  which  is  also  used  in  compression  ma- 
chines, is  a  mixture  of  carbonic  acid  and  sulphurous  acid, 
which,  according  to  Pictet,who  introduced  the  same,  cor- 
responds to  the  formula  CO4  S.  According  to  Pictet,  the 
pressure  of  this  mixture  or  compound  at  higher  tempera- 
ture is  less  than  the  law  of  pressure  relating  to  ordinary 
mixtures  would  indicate.  The  following  table  shows  the 
relations  of  pressures  and  temperatures  of  this  substance: 


Pressure 

Pressure 

Temperature, 
Degrees  F. 

(Absolute) 
in 
Atmospheres. 

Temperature, 
Degrees  F. 

(Absolute) 
in 
Atmospheres. 

—22 

0.77 

50 

2.55 

—13 

0.89 

59 

2.98 

—  4 

0.98 

68 

3.40 

—  2.2 

1.00 

77 

3.92 

5 

1.18 

86 

4.45 

14 

1.34 

95 

5.05 

23 

1.60 

104 

5.72 

32 

1.83 

113 

6.30 

41 

2.20 

122 

6.86 

If  the  Pictet  liquid  were  an  ordinary  mixture  its 
pressure  would  gradually  rise  from  0.77  to  13.98  atmos- 
pheres from  the  temperature — 22  to  +112  degrees  Fahren- 
heit. Instead  of  that  the  pressure  increases  from  0.77 
to  6.86  atmospheres  only,  and  at  77°  F.  is  less  than  that 
of  the  sulphurous  "  acid  "  or  sulphur  dioxide  alone. 

ANOMALOUS  BEHAVIOR  OF  PICTET'S  LIQUID. 

It  is  claimed  that  a  compression  plant,  if  operated 
with  Pictet's  liquid,  will  produce  a  greater  effect  than 
what  is  compatible  with  the  familiar  thermodynamic 
formula  given  on  page  71  of  this  compend.  This  anoma- 
lous behavior  is  sought  to  be  explained  by  the  physical  or 
chemical  work  done  by  the  liquids  while  combining  into 
one  substance  in  the  condenser,  which  work  it  is  argued 
replaces  part  of  the  work  which  would  have  to  be  done  if 


OTHER  COMPRESSION  SYSTEMS.  2oJ 

a  simple  working  fluid  were  used.  If  this  explanation 
were  correct  we  would  have  to  assume  that  while  a  cer- 
tain amount  of  work  (i.  e.  heat)  is  given  off  in  the  con- 
denser, an  equivalent  amount  of  heat  must  be  absorbed 
in  the  refrigerator,  thus  increasing  the  efficiency  of  the 
machine  in  two  directions,  a  most  happy  coincidence,  but 
one  which  is  in  no  wise  corroborated  by  the  second  law  of 
thermodynamics. 

OTHER  EXPLANATIONS  FOR  THE  ANOMALY. 

In  accordance  with  thermo-chemical  tenets,  the 
combination  of  carbonic  and  sulphuric  dioxide  should  ab- 
sorb heat  while  being  formed  in  the  condenser,  and 
should  generate  heat  while  being  decomposed  in  the  re- 
frigerator. Such  a  behavior  would  bring  the  working  of 
a  machine  with  Pictet's  liquid  within  the  scope  of  the 
second  law,  but  it  would  hardly  account  for  the  alleged 
anomalous  efficiency  of  such  a  machine. 

Generally  it  is  supposed  that  the  influence  of  heat 
on  chemical  combinations  is  such  that  they  become  less 
permanent  with  increase  of  temperature,  and  that  at  a 
very  high  temperature  they  are  dissolved  in  their 
elements.  This  is  quite  correct  for  such  combinations 
which  are  formed  by  the  development  of  heat,  and 
which  absorb  heat  while  being  decomposed.  But  the 
contrary  takes  place  in  the  case  of  combinations  which 
are  formed  under  absorption  of  heat.  These  latter  com- 
binations become  more  permanent  with  the  increase  of 
temperature. 

BLUEMCKE  ON  PICTET'S  LIQUID. 

According  to  experiments  made  by  Bluemcke  the 
pressure  of  Pictet's  liquid  is  always  higher  than  that  of 
sulphurous  acid  at  all  temperatures.  Furthermore  he 
claims  that  the  commercial  "Pictet's  liquid"  is  not 
compounded  after  the  formula  CO4  >$,  but  that  it  contains 
only  3  percent  of  CO2  by  volume.  The  mixture  CO,6 
S7,  for  which  Pictet  has  established— 76°  as  the  boiling 
point  has  a  tension  of  four  atmospheres  at  a  temperature, 
of — 17C  C.  Such  conflicting  statements  as  these  are 
hardly  calculated  to  remove  the  doubts  connected  with 
the  use  of  Pictet's  liquid,  and  more  authentic  experi- 
ments by  disinterested  parties  and  with  liquids  of  well 
known  composition  will  be  required  to  definitely  settle 
this  matter. 


l>r,4  MECHANICAL  REFRIGERATION. 

MOTAY  AND  ROSSI'S  SYSTEM. 

Previous  to  Pictet's  invention  Motay  and  Rossi  had 
operated  a  refrigerating  machine  on  a  similar  plan  with 
a  compound  of  two  liquids,  one  of  which  liquefies  at  a 
comparatively  low  pressure  and  then  takes  the  other  in 
solution  by  absorption.  Their  mixture  consisted  of  or- 
dinary ether  and  sulphur  dioxide  and  has  been  termed 
ethylo-sulphurous  dioxide.  It  is  stated  that  the  liquid 
ether  absorbs  300  times  its  volume  of  sulphur  dioxide  at 
ordinary  temperature  and  at  60°  F.  the  tension  of  the 
vapor  of  the  mixture  is  below  that  of  the  atmosphere. 
The  compressing  pump  has  less  capacity  than  would  be 
required  for  ether  alone,  but  more  than  for  pure  sulphur 
dioxide. 

Before  exact  formulsB  can  be  given  for  the  dimen- 
sions and  efficiency  of  machines  working  with  compound 
liquids  their  chemical  and  physical,  and  especially  their 
thermo-chemical  behavior,  must  be  more  definitely  settled 
by  experiments. 

CRYOGENE— REFRIGERATING  AGENTS. 

Cryogene  is  another  name  for  refrigerating  medium, 
and  literally  translated  means  ice  generator.  Certain 
hydrocarbons,  naphtha,  gasoline,  rhigoline  or  chimo- 
gene  have  also  been  recommended  and  used  to  some  ex- 
tent as  refrigerating  media.  These  liquids  are  used  in 
much  the  same  way  as  ether,  in  common  with  which 
they  have  a  great  inflammability;  but  they  are  much 
cheaper  to  start  with.  Van  der  Weyde's  refrigerating 
machine  consists  of  an  air  pump  and  a  force  pump,  a 
condenser  and  two  refrigerator  coils,  one  of  which  also 
serves  as  a  reservoir  for  the  condensed  liquid.  The 
water  to  be  frozen  is  placed  in  molds  which  are 
surrounded  by  a  glycerine  bath.  The  glycerine  bath  in 
turn  is  surrounded  on  the  outside  by  the  refrigerating 
medium,  naphtha,  gasoline,  chimogene,  etc.,  which  is 
evaporated  by  means  of  the  air  pump,  thereby  abstract- 
ing sufficient  heat  to  cause  the  formation  of  ice. 

ACETYLENE. 

Acetylene,  which  has  lately  been  so  prominently 
mentioned  as  the  illuminating  agent  of  the  future,  has 
also  been  talked  of  as  a  refrigerating  agent.  Jt  is  a  com- 
bination of  hydrogen  and  oxygen  after  the  formula  (72  H2. 
It  is  highly  inflammable  and  said  to  require  a  pressure  of 
48  atmospheres  to  be  liquefied  at  freezing  point  of  water. 


AIR  AND   VACUUM  MACHINES.  255 

CHAPTER  XII.— AIR  AND  VACUUM  MACHINES. 

COMPRESSED  AIR  MACHINE. 

Air  is  used  in  various  ways  as  a  working  fluid  in  re- 
frigerating plants,  but  on  the  whole  to  a  limited  extent 
only. 

The  compressed  air  machine  is  based  on  the  utiliza- 
tion of  the  reduction  of  temperature  which  takes  place 
when  compressed  air  expands  while  doing  work  in  an  air 
engine.  The  air  is  compressed  by  a  compressor  and  the 
heat  which  is  generated  by  compression  is  withdrawn  by 
cooling  water.  The  cold  air  leaving  the  expansion  en- 
gine is  used  for  cooling  purposes. 

CYCLE  OF  OPERATIONS. 

This  may  be  done  in  such  a  way  that  the  air  having 
served  for  refrigerating  purposes  is  periodically  returned 
to  the  compressor  in  the  same  condition.  In  this  case 
the  operations  of  the  refrigerating  system  constitute 
what  is  termed  a  perfect  cycle,  and  the  thermodynamic 
laws  applicable  to  such  a  cycle  obtain  also  in  the  case 
of  the  compressed  air  machine. 

Practically  it  is  far  more  convenient  to  reject  the 
working  fluid  (air)  along  with  the  refrigeration,  but  for 
the  purposes  of  the  following  calculations,  which  are 
rendered  after  Ledoux,  we  will  assume  that  the  opera- 
tions of  a  cycle  are  fully  performed. 

WORK  OF  COMPRESSION. 

For  the  work,  TPr,  of  compression  of  the  air,  which  is 
supposed  to  be  done  adiabatically  (without  losing  or  gain- 
ing heat),  Ledoux  gives  the  following  formula: 

Wr  =  k^p  (Pt  Vt  -  P0  F0)  foot-pounds; 
and  also— 

Wr  =  -^|—  (TL  -  TO )  foot-pounds. 

A. 

In  these  equations  P0  and  T0  are  the  initial  press- 
ure and  temperature  of  the  air,  counted  from  absolute 
zero. 

F0  is  the  volume  described  by  the  piston  of  the  com- 
pressor cylinder. 

Ft  is  the  volume  described  by  the  same  piston  during 
the  outflow  of  the  compressed  air. 

P,  and  2\  are  the  temperature  and  pressure  of  the 
compressed  air  when  leaving  the  compressor, 


256  MECHANICAL  REFRIGERATION. 

A  is  the  reciprocal  of  the  mechanical  equivalent  of 
heat  =  yf  ?. 

k  is  the  ratio  of  specific  heat  of  constant  pressure  to 
the  specific  heat  of  constant  volume. 

0.23751 
"0.16844  ~ 

In  the  following  equations: 

m  stands  for  the  weight  of  air  (in  pounds)  whose 
volume  passes  from  V0  to  Ft. 

c  stands  for  the  specific  heat  of  air  of  constant 
volume. 

P2  and  T2  are  the  pressure  and  temperature  of  the 
air  after  expansion. 

F2  is  the  volume  of  the  expansion  cylinder. 

TEMPERATURE  AFTER  COMPRESSION. 

The  temperature,  TA,  of  the  air  after  adiabatic  com- 
pression may  be  found  after  the  following  formulae : 

1.          1 

(~p 
1  1 
P 
^O 

rp    71     /  V" 

•*!  ^0  I   -I-®. 


COOLING  OF  THE  AIR. 

The  air  after  having  been  compressed  is  cooled  down 
from  the  temperature  Tt  to  the  temperature  T3,  and 
volume  F3,  and  the  quantity  of  heat,  #±,  which  must  be 
withdrawn  from  the  air  to  accomplish  this  is— 

Qt  —  m  k  c  (T±  —  T3)  units. 

AMOUNT  OF  WATER  REQUIRED. 

The  amount  of  cooling  water,  P±,  required  is— 


8.8  (-t. 

t  and  «t  being  the  respective  temperatures  of  incoming 
and  outgoing  condenser  water. 

WORK  DONE  BY  EXPANSION. 

The  work,  Wm,  which  may  be  obtained  theoretically 
Jt>y  allowing  the  air,  after  being  cooled,  to  expand  against 


Alii  AND    VACUUM  MACHINES.  ^>< 

a   piston   adiabatically   until    the    temperature  2\  is 
reached  is  : 

Wm  =  ^-l{Pl  V3  —  P2  F2)  foot-pounds. 
or 

Wm  —  y^-  (T3—T2)  foot-pounds. 

A. 
TEMPERATURE  AFTER  EXPANSION. 

The  temperature,  T2,  of  the  air  after  expansion  is 
found  after  the  formula  : 


T8  and  Pt  being  the  temperature  and  pressure  of  the  air 
when  entering  the  expansion  cylinder. 

REFRIGERATION  PRODUCED. 

The  refrigeration,  H,  which  is  produced  by  the  air 
during  adiabatic  expansion  is  expressed  by  — 

H=  m1cc(T0  —  T2)  units, 

T0  being  the  temperature  of  the  air  after  it  leaves  the 
refrigerator. 

WORK  FOR  LIFTING  HEAT. 

The  net  work,  W,  therefore  which  is  theoretically 
required  to  lift  the  amount  of  refrigeration,  Ht  is  ex- 
pressed by  the  formula  — 

W=  Wr  —  Wm  foot-pounds,  or  also- 

^  _  TQ}  _(TS_  7>)  J  foot.poundB. 

EQUATION  OF  CYCLE. 

If  the  quantities,  Qlt  H  and  Wr  and  Wm  are  ex- 
pressed in  the  same  (thermal)  units,  the  equation  of  the 
cycle  of  operations  may  be  expressed  by— 


\f  Wr  and  Wm  are  expressed  in  foot-pounds 


258  MECHANICAL,    REFRIGERATION. 

EFFICIENCY  OF  CYCLE. 

The  theoretical  efficiency,  E,  of  this  refrigerating 
cycle  may  be  expressed  by  the  formula: 


w 


T  T 

and  ~-  being  equal  7,,—  ,  we  also  find  — 


This  expression  is  the  same  as  that  found  for  the 
maximum  theoretical  efficiency  of  a  reversible  refriger- 
ating machine,  page  71. 

The  above  formulae  apply  also  in  case  any  other  per- 
manent gas  is  employed  in  place  of  air. 

SIZE  OF    CYLINDERS. 

From  the  above  equations  the  relative  sizes  Fand  V2 
of  compression  and  expansion  cylinders,  for  a  given 
amount  of  refrigeration  in  a  given  time,  can  be  readihr 
ascertained  for  theoretical  conditions. 

The  ratio  which  should  exist  between  the  volumes 
of  the  two  cylinders  in  order  that  the  air  is  expelled  at 
atmospheric  pressure  is  expressed  by  the  following 
equations  : 

V* 

- 


V,  T3 


V3  standing  for  the  volume  of  air  after  compression 
and  after  subsequent  cooling,  when  it  has  the  tempera- 
ture T3. 

ACTUAL  EFFICIENCY. 

Owing  to  the  bulkiness  of  air,  the  compression  and 
expansion  cylinders  have  to  be  very  large,  a,  fact  which 
tends  to  increase  the  friction  considerably.  Besides  this 
there  is  considerable  clearance,  and  the  moisture  con- 
tained in  the  air  also  decreases  the  efficiency,  all  of 
which  circumstances,  combined  with  others  of  minor 
importance,  reduce  the  actual  performance  of  the  air 
machine  muclj  below  the  theoretical  efficiency. 


AIR  AND  VACUUM:  MACHINES. 
RESULTS  OF  EXPERIMENTS. 


250 


The  foregoing  remarks  are  forcibly  illustrated  by  the 
following  tests  of  compression  machines,  which  were 
published  by  Linde  some  time  ago.  The  figures  in  this 
table  show  that  in  the  most  favorable  experiment  (Light- 
foot)  the  actual  efficiency  is  scarcely  33  per  cent  of  the 
theoretical  efficiency.  (After  Ledoux  the  friction  alone 
reduces  the  theoretical  refrigerating  for  about  25  per 
cent.) 

ACTUAL  PERFORMANCE   OF  COLD    AIR  MACHINES. 


SYSTEM  

Bell- 

Lightfoot 

Haslam 

Colem'n. 

TE^T  No                       

1 

2 

3 

Diameter  of  compression  cylin- 
der            

28" 

j        27" 
|  s'gle  act'gr 

j     25H" 
1  2-cylinder 

Diameter  of  expansion  cylinder 
Diameter  of  steam  cylinder 

21" 
21" 

22" 

j     19K" 
I  2-cylinder 
l    20"  H.  P. 

Stroke  of  all  cylinders  
Revolutions  per  minute  
Air  pressure  in  receiver,  pounds 

24" 
63.2 

61 

18" 
62 

65 

(    31"  L.  P. 
36" 

72 

64 

Temperature  of  air  entering  the 
compression  cylinder 

65H°  F 

52°  F. 

Temperature  of   air   after  ex- 
pansion.                      

—52.6°  F. 

—82°  F. 

—85°  F. 

I.  H.  P.  in  compression  cylinder 
I.  H.  P.  in  expansion  cylinder.. 
I.  H.  P.  in  steam  cylinder  
B.  T.  U.   abstracted    per  hour 
and  I.  H.  P.  of  steam  cylinder 
at  20°  F 

124.5 

58.5 
84.4 

668 

43.1 

28.0 
24.6 

1,554 

346.4 
176.2 
332.7 

954 

The  figures  for  test  No.  1  have  been  observed  and 
published  by  Professor  Schroeter(  Untersuchungen  an  Kcelte- 
maschinen  verschiedener  Systeme,  Munich  (1887);  those  for 
No.  2  are  published  in  minutes  Proc.  Inst.  Mecfi.  Eng., 
London,  1881.  The  data  for  trial  No.  3  are  taken  from 
a  paper  read  last  year  before  the  Manchester  Society  of 
Engineers. 

WORK  REQUIRED  FOR  ISOTHERMAL  COMPRESSION. 

If  the  compression  of  air  takes  place  isothermically, 
in  which  case  the  air  is  kept  at  constant  temperature 
during  compression  by  injection  of  cold  water  and  a  cold 
water  jacket,  the  work  of  compression  is  lessened.  The 
work  W2  in  foot-pounds  required  in  theory  to  compress 
isothermically  V  cubic  feet  of  air  under  a  pressure  of 


2GO 


MECHANICAL  REFRIGERATION. 


P  pounds  (per  square  foot)  to  the  volume  of  Vt  cubic 
feet  is— 

W=  P  VX  2.3026  log  ^-  foot-pounds. 
" 


WORK  DONE  IN  ISOTHERMAL  EXPANSION. 

The  work,  Wlt  in  foot-pounds  which  can  be  done 
theoretically  by  the  isothermal  expansion  of  Fx  cubic 
feet  of  air  to  the  volume  of  V  cubic  feet,  and  the  press- 
ure P  is  — 

W,  =  P  VX  2.3026  log  — 

OTHER  USES   OF  COMPRESSED  AIR. 

The  isothermal  expansion  of  air  is  employed  in  cases 
where  compressed  air  is  used,  not  for  refrigeration,  but 
for  the  production  of  power,  as  in  tunneling,  drilling  in 
mines,  transmission  of  power  by  compressed  air,  etc. 
These  are  purposes  for  which  the  compressed  air  has 
been  extensively  used. 

TABLE    SHOWING    LOSS    OF    PRESSURE     BY    FRICTION    OF 
COMPRESSED  AIR  IN  PIPES. 

(F.  A.  Halsey.) 


Diameter 
of  Pipe. 

Cubic  Feet  of  Free  Air  compressed  to  a  Gauge  Pressure  of 
60  Ibs.  per  Square  Inch,  and  passing  through 
the  Pipe  per  Minute. 

50 

75 

100 

125 

150 

200 

250 

300 

400 

600 

Loss  of  Pressure  in  Pounds  per  Square  Inch  for  each  1,000 
Feet  of  Straight  Pipe. 

Ins. 
1 

1& 

$ 

2/2 

3 

31/2 

5 
6 

Lbs. 

10.40 
2.63 
1.22 
.35 
.14 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

5  90 

2.75 
.79 
.32 
.11 

4.89 
1  41 
.57 
.20 

7.65 
2.20 
.90 
.31 
.15 

11.00 
3.17 
1.29 
.44 
.21 

5.64 
2.30 

.78 
.38 
.20 

8.78 
3.58 
1.23 
.59 
.31 
.10 

'5.18 
1.77 
.85 
.45 
.15 

'9]20' 
3.14 
1.51 
.80 
.26 

'i'.05 
3.40 
1.81 
.69 
.23 

CALCULATED  EFFICIENCY. 

The  best  working  pressure  for  a  compression  air  ma- 
chine appears  to  be  at  4>£  atmospheres,  and  the  calcula- 
tions for  this  pressure  give,  according  to  Denton,  a  theo- 
retical efficiency  of  17. 5  pounds  ice  melting  capacity  per 
pound  of  coal  (assuming  three  pounds  of  coal  per  horse 
power).  Allowing  for  friction,  one  pound  of  coal  should 


AIR  AND  VACUUM  MACHINES.  261 

give  a  refrigerating  effect  equivalent  to  eleven  pounds 
ice  melting  capacity  with  a  consumption  of  nine  gallons 
of  water.  ( T0  =  59°  F.  and  T3  =  64.4°  F.  weight  of  one 
cubic  foot  of  air  with  0.0357  pounds  of  moisture  =0.07524 
pounds.) 

LIMITED  USEFULNESS. 

In  consequence  of  the  low  practical  efficiency  the  air 
compression  system  is  impracticable  for  indirect  refrigera- 
tion, and  can  best  be  used  where  cold,  dry  air  is  the 
ultimate  object,  and  even  in  this  case  its  economical 
adaptability  seems  to  depend  on  circumstances. 

One  of  the  chief  difficulties  in  cold  air  machines, 
says  Gale,  is  the  presence  of  moisture  held  in  suspension 
by  the  atmosphere.  Moisture  in  the  air  occasions  loss  of 
efficiency  in  two  ways.  If  the  air  enters  the  expansion 
cylinder  in  a  saturated  condition,  when  the  air  is  cooled 
by  expansion  while  performing  work,  a  certain  amount 
of  vapor  is  condensed  and  thrown  down— the  point  of 
saturation  being  dependent  on  the  temperature.  The 
vapor  in  changing  to  a  liquid  state  gives  its  latent  heat 
of  vaporization  to  the  air ;  and  as  the  expansion  of  the 
air  continues  and  the  temperature  is  still  further  dimin- 
ished, the  liquid  freezes  and  accumulates  in  the  form  of 
snow  or  ice  in  the  valves  and  passages,  giving  up  its  heat 
of  liquefaction  to  the  air.  Thus  does  not  only  the  pres- 
ence of  moisture  in  the  air  produce  mechanical  difficul- 
ties, choking  the  air  passages  and  impeding  the  action 
of  the  valves,  but,  for  the  same  expenditure  of  energy, 
the  cold  air  leaves  the  machine  at  a  higher  temperature 
than  would  have  been  the  case  if  there  had  not  been  a 
superabundance  of  moisture  in  the  air  during  expansion, 

VACUUM    MACHINES. 

With  the  name  of  vacuum  machines  is  designated 
a  class  of  refrigerating  apparatus  in  which  water  is  used 
as  a  refrigerating  agent.  In  their  most  simple  form 
they  work  on  the  same  principle  as  a  compression  ma- 
chine. The  vaporization  of  the  water  at  a  temperature 
low  enough  to  cause  the  freezing  of  the  water  must  take 
place  under  vacuum.  The  vacuum  is  formed  by  a  vacuuifi 
pump  which  acts  exactly  like  a  compressor,  withdrawing 
the  vapors  or  vapor  from  the  refrigerator  where  the 
pressure  is  about  0.1  pound  per  square  inch,  and  com- 


262  MECHANICAL  REFRIGERATION . 

pressing  the  same  into  a  condenser  against  a  pressure  of 
about  1.5  pounds  per  square  inch. 

REFRIGERATION   PRODUCED. 

The  refrigeration  produced  by  the  evaporation  of  a 
part  of  the  water  in  the  refrigerator  causes  a  correspond- 
ing portion  of  the  water  to  turn  into  ice.  As  the  latent 
heat  of  ice  is  about  142  and  that  of  the  watery  vapor 
about  940,  theoretically  the  evaporation  of  one  pound  of 
water  would  be  able  to  produce  from  six  to  seven  pounds 
of  ice. 

EFFICIENCY  AND   SIZE. 

The  efficiency,  dimensions,  etc.,  of  a  vacuum  machine 
if  worked  on  the  plan  of  reversible  cycle  may  be  calculated 
by  the  same  rules  given  for  the  ammonia  compressor.  As 
the  latent  heat  of  watery  vapor  is  very  great  in  com- 
parison to  the  specific  heat  of  the  liquid  (see  page  87)  the 
theoretical  efficiency  of  a  vacuum  machine  will  be  found 
considerably  greater  than  that  of  the  other  compression 
machines. 

This  seeming  advantage,  however,  is  more  than 
counterbalanced  by  the  enormous  size  of  the  compressor 
required  on  account  of  the  low  tension  of  the  water 
vapor  at  the  temperature  of  the  refrigerator.  It  is  found 
that  the  compressor  or  vacuum  pump  of  a  vacuum  ma- 
chine of  a  certain  capacity  will  have  to  be  about  200 
times  as  large  as  that  of  an  ammonia  compression  ma- 
chine of  the  same  capacity. 

If  the  temperatures  to  be  produced  by  a  vacuum  ma- 
chine are  to  be  lower  than  that  of  freezing  water,  a 
solution  of  salt  has  to  be  placed  in  the  refrigerator  in- 
stead of  pure  water,  to  prevent  the  freezing  of  the  re- 
frigerating agent. 

COMPOUND  VACUUM  MACHINE. 

In  order  to  avoid  compressors  of  such  an  enormous 
size  the  foregoing  form  of  a  vacuum  machine  has  been 
complicated  by  the  addition  of  an  absorbent,  preferably 
concentrated  sulphuric  acid,  which,  by  means  of  its  ab- 
sorbent power  for  watery  vapor,  releases  the  work  of  the 
compressor  or  air  pumps.  A  machine  of  this  construc- 
tion works  on  nearly  the  same  principle  as  an  absorption 
machine,  and  its  efficiency,  etc.,  may  be  discussed  on  the 
same  basis. 


AIR  AND    VACUUM  MACHINES.  263 

In  the  machines  constructed  on  the  latter  principle, 
which  vary  considerably  in  detail,  the  fuel  used  to  recon- 
centrate  the  sulphuric  acid  (which  has  become  diluted 
from  60°  to  52°  Beaume)  represents  one  of  the  principal 
expenses.  The  vacuum  pump  is  small,  but  in  continuous 
operations  there  must  also  be  a  pump  for  the  exchange 
of  the  diluted  and  concentrated  acid. 

This  exchange  is  performed  in  such  a  way  that  the 
cold,  weak  acid  leaving  the  absorber  withdraws  the  heat 
from  the  strong  acid  coming  from  the  evaporator. 

EXPENSE  OF  OPERATING. 

The  larger  part  of  the  heat  withdrawn  from  the 
water  or  salt  brine  in  the  refrigerator  appears  again  in 
the  absorber  as  heat  of  combination  between  the  sul- 
phuric acid  and  the  vapor.  It  is  removed  by  cooling 
water. 

It  is  stated  that  for  the  production  of  100  pounds  of 
ice  it  will  take  about  eight  pounds  of  coal  in  the  evapo- 
rator and  about  twelve  gallons  of  cooling  water.  Besides 
this  we  must  allow  for  the  power  required  to  operate  the 
vacuum  and  acid  pumps. 

OBJECTIONS  TO  SULPHURIC  ACID. 

The  vessels  and  pipes  containing  or  carrying  the  sul- 
phuric acid  must  be  of  lead  or  lead  lined,  and  on  the 
whole  the  handling  of  this  liquid  is  considerable  of  an  in- 
convenience. For  this  and  other  reasons  the  use  of  the 
vacuum  machine  will  probably  be  confined  to  special 
cases.  The  making  of  ice  in  connection  with  some  other 
industry  requiring  the  production  of  diluted  sulphuric 
acid  on  a  large  scale,  and  at  a  great  distance  from  the 
sulphuric  acid  factory,  would  be  such  a  case. 

SOUTHBY'S  VACUUM  MACHINE. 
The  apparent  simplicity  and  directness  of  action  of 
a  vacuum  machine  for  the  direct  production  of  ice  has 
produced  several  inventions  in  this  direction.  In  a  ma- 
chine designed  by  Southby  &  Blyth,  the  freezing  can,  or 
cans,  containing  the  water  to  be  frozen  is  placed  in  a  box, 
which  can  be  closed  air  tight,  and  from  this  box  the  air, 
and  eventually  the  watery  vapor,  is  exhausted  by  means 
of  two  pumps  of  peculiar  construction.'  One  is  an  air 
pump  which  is  designed  to  draw  all  the  air  from  the  in- 
terior of  the  machine,  and  the  vacuum  so  formed  fills 


264  MECHANICAL  REFRIGERATION. 

itself  with  watery  vapor  from  the  water  in  the  freezing 
can.  A  second  larger  pump  then  compresses  the  vapor 
and  forces  the  same  into  the  condenser.  But  in  order  to 
do  this  effectually  the  condensation  of  vapor  in  the  com- 
pressor has  to  be  prevented,  as  otherwise  the  tension  of 
the  compressed  vapor  to  be  ejected  would  be  so  small  in 
quantity  that  it  would  not  be  forced  through  the  exit 
valve.  To  accomplish  this  the  cylinder  of  the  large  pump 
is  heated  to  a  temperature  above  that  at  which  the  vapor 
will  condense,  and  in  this  way  the  compressed  vapor  is 
almost  entirely  forced  into  the  condenser.  The  water 
forming  in  the  condenser,  together  with  the  air  drawn 
over  from  the  water,  etc.,  is  ejected  by  the  small  air  pump. 
The  small  air  pump,  in  connection  with  the  large 
compressor,  and  the  heating  of  the  latter,  are  the  two 
principal  new  features  which  are  claimed  to  insure  the 
success  of  this  machine.  Owing  to  the  low  pressures 
(from  0.15  to  2  inches,  average  pressure  on  piston  1-6 
pound  per  square  inch)  the  frictureof  the  compressor  can 
be  made  very  small. 

OPERATING  SOUTHBY'S  MACHINE. 
When  starting  the  machine  air  at  a  comparatively 
high  pressure  has  to  be  dealt  with,  occasioning  an  ad- 
verse pressure  on  the  piston  of  say  seven  pounds,  or  over 
thirty  times  that  of  the  working  pressure;  and  the  air 
being  non-condensible  will  not  disappear  on  com- 
pression, as  is  the  case  with  watery  vapor.  For  this 
reason,  provision  has  been  made  that  both  ends  of  the 
vapor  pump  cylinder  can  be  kept  open  for  any  neces- 
sary length  of  time  during  the  first  portion  of  the  deliv- 
ery stroke,  so  as  to  permit  the  air  to  return  to  the  under 
side  of  the  piston  and  thereby  lessen  and  regulate  the 
expenditure  of  power  to  be  expended  in  obtaining  a 
vacuum.  This  is  accomplished  by  means  of  a  by-pass 
and  valve,  which  can  be  opened  at  starting,  and  kept 
open  for  about  nine-tenths  of  the  piston  stroke,  being 
closed  gradually  as  soon  as  the  vacuum  becomes  more 
perfect,  and  altogether  as  soon  as  all  the  air  has  been 
got  rid  of.  According  to  British  writers  the  manufact- 
urers of  this  machine  intend  the  same  to  be  used  in 
confined  places,  on  board  ship,  or  where  the  escape  of 
injurious  gases  would  be  dangerous,  also  for  making  ice 
by  hand  power.  The  quantity  of  cooling  water  for  the 
condenser  is  said  to  be  very  small  indeed. 


LIQUEFACTION  OF  GASES.  265 

CHAPTER  XIIL-LIQUEFACTIOtf  OF  GASES. 

HISTORICAL  POINTS. 

The  liquefaction  of  the  formerly  so  called  permanent 
gases  has  always  attracted  considerable  attention  on  the 
part  of  physicists  and  chemists  as  a  means  of  studying 
matter  in  different  states  of  aggregation,  and  also  as 
means  of  producing  extremely  low  temperatures.  The 
names  of  Faraday,  Thilorier,  Natterer,  De  La  Tour,  and, 
more  recently  Pictet,  Cailletet,  Wroblewski,  Olszewski, 
Dewar  and  others  have  become  famous  in  connection 
with  this  subject. 

The  former  methods  used  for  liquefaction  of  gases  on 
a  larger  scale  than  the  bent  tubes  used  by  Faraday,  etc., 
and  which  until  recently  were  also  employed  by  Dewar  in 
the  production  of  larger  quantities  of  liquid  oxygen,  etc., 
were  practically  identical  with  those  originated  by  Pictet 
and  Cailletet,  who  in  addition  to  pressure  used  a  suc- 
cession of  various  cooling  agents  (liquefied  gases),  one 
cooling  the  next,  and  so  on,  until  at  last  a  temperature 
was  reached  low  enough  to  liquefy  the  gas  in  hand. 

Although  large  quantities  of  liquid  gases  could  be 
prepared  in  this  manner,  and  could  be  experimented 
upon,  still  their  production  was  extremely  expensive, 
and  therefore  the  whole  subject  was  confined  to  scientific 
studies  and  experiments. 

These  costly  methods,  however,  have  been  replaced 
within  recent  years  by  more  practical  operations,  which 
render  the  liquefaction  of  the  most  permanent  gases  an 
easy  and  comparatively  inexpensive  task,  and  have  made 
the  subject  one  of  general  and  perhaps  practical  interest. 

SELF-INTENSIFYING  REERIGERATION. 

This  surprising  result  was  consummated  by  Prof. 
Linde,  the  originator  of  the  ammonia  compression  sys- 
tem of  refrigeration,  who  inaugurated  and  perfected  a  self - 
intensifying  refrigerating  method,  by  which  the  lique- 
faction of  gases,  notably  air,  oxygen,  nitrogen,  can  be 
carried  out  on  a  large  scale  and  at  moderate  cost.  The 
first  large  apparatus  working  on  Linde's  new  plan  was 
exhibited  before  a  body  of  physicists,  chemists  and  engi- 
neers in  Munich  in  the  month  of  May,  1895,  and  then 
and  there  large  quantities  of  liquid  air  were  produced  at 
the  rate  of  several  quarts  per  hour. 

The  principles  upon  which  Linde's  apparatus  works 
are  very  ingeniously  conceived,  and  the  ingenuity  dis- 


266  MECHANICAL  REFRIGERATION. 

played  in  this  direction  are  only  equaled  by  the  simplicity 
in  the  construction  of  the  apparatus  itself. 

Linde  dispenses  entirely  with  the  use  of  auxiliary 
refrigerants,  but  makes  the  gases  themselves  supply  the 
refrigeration  required  for  their  liquefaction,  by  means 
exclusively  mechanical;  i.  e.,  by  the  use  of  an  ordinary 
compressor,  exchanger,  water  cooler,  expansion  valve  and 
liquid  receiver. 

LINDE'S  SIMPLE  METHOD. 

The  gas  to  be  liquefied,  atmospheric  air  for  example, 
is  taken  in  by  a  compressor,  and  after  compression  is 
forced  through  an  ordinary  water  cooler  to  dispose  of  the 
heat  of  compression;  thence  it  is  forced  through  a  coil 
several  hundred  feet  long,  the  end  of  which  is  provided  with 
an  expansion  valve,  which  dips  into  a  liquid  receiver  or 
collection  vessel;  from  this  vessel  issues  another  pipe,  which 
forms  a  coil  surrounding  (forming  an  annular  concentric 
space)  the  coil  previously  mentioned,  and  which  returns 
the  air  (after  having  expanded  into  the  liquid  receiver) 
to  the  compressor.  The  compressed  air  while  expanding 
into  the  liquid  receiver,  against  pressure,  as  it  were,  does 
a  certain  amount  of  (interior)  work,  and  generates  a 
corresponding  amount  of  refrigeration;  i.  e.,  it  lowers  its 
own  temperature  correspondingly.  In  this  condition  the 
air  flows  back  to  the  compressor,  and  on  the  way,  while 
passing  around  the  coil  through  which  the  compressed 
air  passes,  cools  the  latter  before  it  enters  the  liquid 
receiver.  The  air  when  it  again  reaches  and  passes  the 
compressor  and  water  cooler  leaves  the  same  with  a 
higher  pressure,  and  again  enters  the  liquid  receiver  at 
lower  temperature  than  it  did  before,  and  in  this  manner 
pressure  and  refrigeration  gradually  increase  in  the 
liquid  receiver  by  what  may  be  termed  an  accumula- 
tive effect,  produced  by  constant  repetitions  of  the  cycle 
of  operations  just  described,  until  finally  the  critical 
temperature  is  reached,  at  which  the  air  liquefies  and 
collects  at  the  bottom  of  the  liquid  receiver,  whence  it 
may  be  withdrawn  by  means  of  a  faucet. 

AS  fast  as  the  air  becomes  more  compressed  and  is 
finally  withdrawn  from  the  cycle  in  its  liquid  form,  other 
air  must  be  supplied  to  the  compressor,  and  as  the  effi- 
ciency of  the  cycle  is  at  its  best  at  very  high  pressure,  the 
original  air  is  already  supplied  to  the  same  in  a  com- 
pressed state  by  an  auxiliary  compressor.  The  system  of 


LIQUEFACTION  OF  GASES.  267 

concentric  coils  forming  the  exchanger  and  the  liquid 
receiver  must  be  inclosed  in  a  chamber  especially  well 
insulated  in  order  to  render  the  apparatus  operative. 

THE  RATIONALE  OF  LINDE'S  DEVICE. 

Several  schemes  of  "regenerative,"  accumulative  or 
self-intensifying  systems  of  refrigeration  and  liquefac- 
tion have  been  proposed  before,  but  none  succeeded  in 
producing  liquid  air  before  Linde,  who  also  was  the  first 
who  clearly  understood  and  pointed  out  the  physical  prin- 
ciples underlying  the  operation,  and  who  gave  numerical 
data  regarding  the  efficiency  of  the  cycle  of  operation  in- 
volved therein. 

Accordingly,  the  performance  of  interior  work  by  the 
very  gas  to  be  compressed  is  the  source  of  the  refrigera- 
tion, which  causes  its  temperature  to  fall  below  the  crit- 
ical point,  at  which  it  is  readily  liquefied  by  pressure. 

It  was  known  long  ago,  and  it  had  been  experiment- 
ally elaborated  some  thirty  years  by  Joule  and  Thompson 
that  the  law  of  Gay  Lussac  did  not  strictly  apply  to  air 
and  some  other  gases,  and  that  a  certain  amount  of  in- 
terior work  (to  overcome  the  mutual  attraction  of  their 
molecules)  was  done  on  expanding;  still,  this  amount  of 
interior  work  (and  corresponding  refrigeration)  was 
deemed  so  insignificant  that  expansion,  while  doing 
actual  mechanical  work  (moving  a  piston  in  an  expansion 
cylinder),  was  considered  indispensable  in  an  air  refriger- 
ating machine.  Linde,  however,  pointed  out  that  this 
refrigeration,  due  to  the  free  expansion  of  a  gas  from  a 
higher  to  a  lower  pressure,  although  small  at  low  press- 
ure, would  increase  very  rapidly  with  the  pressure  in  an 
apparatus  working  on  the  accumulative  principle. 

The  increase  of  the  heat  elimination  with  the  press- 
ure, and  the  economic  principle  of  Linde's  method,  be- 
come readily  apparent  when  we  analyze  the  formula 
which  expresses  the  relation  between  the  lowering  of 
temperature  d  and  the  pressure  p  before  and  the 
pressure  pt  after  expansion.  In  this  formula— 


T  is  the  temperature  at  which  the  compressed  gas  ex- 
pands in  degrees  absolute  Fahrenheit;  the  pressures  are 
expressed  in  atmospheres. 

The  fall  of  temperature  of  a  gas  during  free  expan- 
sion from  a  higher  to  a  lower  pressure  is  frequently 


268  MECHANICAL  REFRIGERATION. 

referred  to  as  the  "Joule  effect,"  or  as  the   "Joule- 
Thompson  effect." 

VARIABLE  EFFICIENCY. 

This  formula  readily  shows  that  the  refrigeration  of 
the  gases  increases  with  the  increase  of  the  difference 
P—Pit tnat  is,  the  difference  of  pressure  on  both  sides  of 
the  expansion  valve;  and  also  with  the  decrease  of  T,that 
is,  with  the  expanding  temperature.  As  the  latter  is 
.constantly  lowered  in  accordance  with  the  accumulative 
principle  on  which  the  apparatus  works,  the  efficiency  of 
the  system  evidently  increases  the  nearer  the  tempera- 
ture of  the  gas  reaches  its  critical  point. 

While  the  degree  of  refrigeration  depends  on  the 
difference,  p—p^  the  amount  of  work  or  power  required 
to  operate  the  apparatus  or  to  force  the  air  round  and 

round  the  circuit  depends  on  the  quotient  JL  or  the  ratio 

Pi 
of  pressure  in  front  and  back  of  the  compressor  piston. 

By  making  JL.  small  and  p— pt  great, which  can  be  done 

by  working  at  very  high  pressures,  the  efficiency  of  the 
system  may  be  brought  near  a  maximum  figure. 

To  accomplish  this,  in  a  measure,  the  air  or  gas  to 
be  liquefied  is  already  brought  to  a  pressure  of  some  fifty 
atmospheres  by  an  auxiliary  compression  before  it  is  fur- 
nished to  the  compressor,  which  operates  the  liquefying 
circuit  proper. 

HAMPSON'S  DEVICE. 

In  keeping  with  the  foregoing  consideration,  Hamp- 
son  has  constructed  a  similar  apparatus,  which  may  be 
operated  with  compressed  air  or  gases  contained  in  cyl- 
inders alone,  and  without  a  compressor  and  water  cooler. 
In  this  case,  only  that  portion  of  the  gas  or  air  which  is 
actually  liquefied  remains  in  the  system;  the  other  por- 
tion is  exhausted  or  wasted,  so  to  speak.  This  appa- 
ratus is  specially  adapted  for  lecture  purposes,  and  is 
only  a  modification  of  Linde's,  well  foreshadowed  in  the 
latter's  original  observations  on  the  subject. ' 

OTHER  METHODS. 

Regarding  the  history  of  Linde's  method  of  liquefac- 
tion, it  may  be  mentioned  that  Siemens,  as  early  as  1857, 
applied  for  a  patent  in  Germany  on  a  self-intensifying 
or  regenerative  process  of  refrigeration,  in  accordance 
with  which  the  air  is  first  compressed  with  an  ordinary 


LIQUEFACTION  OF  GASES.  269 

compressor,  and  then  expanded  in  a  motor  cylinder, 
whereby  the  temperature  is  reduced;  the  air  is  then 
passed  through  an  exchanger,  in  which  it  is  cooled  by  the 
compressed  air  which  enters  the  exchanger  from  the 
opposite  side.  Siemens  did  not  attempt  to  carry  out  his 
invention,  it  appears,  but  in  1885  Solvay  patented  a 
similar  device  and  put  the  same  in  operation,  but  did 
not  succeed  in  obtaining  temperatures  lower  than 
— 140°  F.,  and  did  not  succeed  in  liquefying  air. 

In  1893  Tripler  obtained  an  English  patent  for  a  gas 
liquefying  apparatus,  and  for  several  years  has  been  pro- 
ducing liquid  air  and  experimenting  with  the  same.  On 
this  fact  it  appears  that  some  people  try  to  establish  the 
priority  of  Tripler  for  the  production  of  liquid  air  by  the 
self-intensifying  process  over  Linde. 

TRIPLER'S    INVENTION. 

In  this  connection,  however,  it  must  not  be  over- 
looked that  Tripler,  no  more  than  Solvay  or  Siemens, 
made  no  mention  in  his  specification  of  the  effect  due  to 
the  air  expanding  against  pressure  through  a  narrow 
orifice  or  expansion  valve,  nor  is  there  any  evidence 
on  record  that  Tripler  made  any  liquid  air  until  a  con- 
siderable time  after  Linde  and  even  Mr.  Hampson  had 
made  the  same  in  large  quantities.  The  latter,  in  writing 
to  the  Engineer  (London,  England),  makes  the  following 
and  apparently  not  unjust  reference  to  Tripler's  dis- 
coveries: 

"So  far  as  is  known  to  the  public,  Mr.  Tripler  can 
only  be  credited  with  three  attainments  of  any  magni- 
tude. In  1893  he  patented  in  this  country  an  invention 
for  liquefying  gases  by  cold,  which  involved  an  obvious 
fallacy  so  gross  and  so  important  to  the  invention  that, 
instead  of  producing  cold,  it  would  actually  produce  heat. 
That  is  attainment  No.  1.  In  1897,  having  imitated 
on  a  larger  scale  my  invention  for  a  self-intensive 
liquefier,  which  had  been  made  and  illustrated  in  detail 
nearly  two  years  before,  he  showed  it  as  an  oiiginal  in- 
vention; and  having  performed,  with  but  slight  variations 
except  their  larger  scale,  experiments  with  which  the 
scientific  world  on  this  side  of  the  Atlantic  had  long  been 
familiar,  he  omitted  all  reference  to  that  fact.  Thirdly, 
in  1899,  in  connection  with  the  working  of  a  liquid  air 
engine,  he  overlooked  the  vital  point  in  the  liquefaction 
of  air  that  the  latent  heat  given  out  in  liquefaction  must 


270  MECHANICAL  REFRIGERATION. 

be  removed  by  some  other  substance  than  the  liquefied 
portion." 

USES  OF  LIQUID  AIR. 

Much  has  been  written  about  the  utilization  of  liquid 
air  in  various  ways,  especially  as  a  motive  power.  It  is 
entirely  superfluous  here  to  assert  the  ^practicability 
of  the  use  of  liquid  air  as  a  vehicle  for  motive  power 
under  ordinary  circumstances.  A  medium  in  which  the 
motive  power  has  to  be  stored  up  at  such  a  low  tempera 
ture,  entailing  the  loss  of  considerable  mechanical 
energy,  could  not  be  considered  economical  for  the  trans- 
fer of  power,  for  this  reason  alone. 

As  a  means  for  the  storage  of  power,  liquid  air  has 
also  been  prominently  mentioned  by  the  lay  press,  but 
the  very  fact  that  it  is  impracticable  to  store  or  main- 
tain it  for  any  length  of  time  under  ordinary  conditions 
with  any  degree  of  safety  or  without  losing  the  larger 
portion  of  the  liquid  precludes  this  idea  altogether. 

Another  reason,  moreover,  for  the  unavailability  of 
liquid  air  as  motive  power  is  to  be  sought  in  the  fact  that 
not  only  mechanical  power,  but  also  considerable  refrig- 
erative  capacity,  is  stored  up  in  this  medium,  for  which  no 
adequate  return  would  be  obtained  if  it  were  used  as  a 
motive  power  for  ordinary  purposes. 

The  circumstance  may  not  exclude  the  possibility  of 
the  use  of  liquid  air  for  motive  power  in  cases  where  ex- 
pense is  of  little  consideration,  and  in  which  certain  con- 
veniences are  aimed  at,  as  for  instance  for  the  throwing 
of  projectiles,  for  the  preparation  of  high  explosives,  for 
the  propelling  of  torpedoes,  for  aerial  navigation  and  in 
other  cases  of  emergency. 

With  regard  to  the  use  of  liquid  air  as  a  refrigerating 
medium,  similar  considerations  do  obtain.  The  expense 
of  its  production  is  too  high  to  render  it  available  for  or- 
dinary refrigeration;  but  where  very  low  temperature  is 
required  for  specific  purposes,  as  for  the  preparation  and 
purification  of  certain  chemicals,  for  medical  uses,  for 
physical  experiments,  etc., liquid  air  and  doubtless  other 
liquefied  gases  have  certainly  many  advantages,  and 
therefore  this  subject  cannot  be  ignored  by  the  pro- 
gressive engineer. 

SPECIFIC  USES  OF  LIQUID  AIR. 

From  among  the  specific  uses  of  liquid  air,  which  al- 
ready have  taken  a  more  practical  form,  we  may  men- 


LIQUEFACTION  OF  GASES.  271 

tion  the  production  of  liquid  oxygen  for  which  Linde 
also  constructed  a  special  apparatus  which  is  based  on 
the  observation  that  when  liquid  air  is  allowed  to  evap- 
orate under  certain  precautions,  the  nitrogen  evaporates 
first,  leaving  a  liquid  containing  50  per  cent  and  more  of 
oxygen. 

The  apparatus  used  by  Linde  for  this  purpose  is  quite 
similar  to  his  liquefaction  apparatus,  the  principal  novel 
feature  of  it  being  an  arrangement  whereby  the  nitrogen 
as  well  as  the  oxygen  is  enabled  to  leave  the  machine  at 
ordinary  temperature.  Thus  the  whole  refrigeration 
bestowed  on  the  gases  during  liquefaction  is  returned  to 
or  retained  in  the  system. 

This  liquid,  consisting  chiefly  of  oxygen,  has  already 
been  put  to  practical  uses  in  the  production  of  very  high 
temperatures.  Inasmuch  as  in  combustions  with  ordi- 
nary air  the  nitrogen,  which  has  to  be  heated  also,  carries 
away  much  of  the  heat  of  combustion,  the  "  Linde  air" 
will  work  a  great  change  in  this  direction. 

Not  only  in  ordinary  combustion,  but  also  in  other 
chemical  oxidizing  processes  in  which  the  presence  of 
nitrogen  lessens  the  affinity,  the  Linde  product  will  be 
of  great  service,  and  is  already  utilized  in  the  manu- 
facture of  chloride  after  the  " Deacon"  process. 

For  illuminating  purposes  the  "Linde  liquid  "  (liquid 
air  containing  over  50  per  cent  oxygen)  will  doubtless 
also  be  made  available,  and  it  is  possible  that  the  electric 
furnace  may  soon  have  a  rival  in  a  furnace  operated  with 
"Linde  air,"  for  it  has  been  reported  already  that  cal- 
cium carbide  has  been  prepared  by  such  a  furnace  without 
the  use  of  electricity. 

Another  interesting  use  of  liquid  air  is  the  rapid 
production  of  high  vacuum.  For  this  purpose  the  vessel 
to  be  exhausted  is  filled  with  a  gas  more  easily  condens- 
able than  air,  say  with  carbonic  acid  gas.  The  vessel  is 
provided  with  an  extension  which  can  be  sealed  off  very 
readily.  The  open  end  of  the  extension  is  then  immersed 
into  liquid  air,  when  the  carbonic  acid  is  withdrawn  from 
the  vessel  and  deposited  in  the  extension,  which  is  then 
sealed  off,  leaving  a  high  vacuum  in  the  vessel. 

TABULATED  PROPERTIES. 

The  accompanying  table  shows  the  physical  constants 
of  a  number  of  gases,  which  have  also  been  studied  in 
the  liquid  states,  as  compiled  by  Peckham. 


272 


MECHANICAL  REFRIGERATION. 


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MANAGEMENT  OF  COMPRESSION  PLANT.  273 

CHAPTER  XIV.— MANAGEMENT  OF  COMPRESS- 
ION PLANT. 

INSTALLATION  OF  PLANT. 

The  installation  of  a  refrigerating  plant  comprises 
the  proper  mounting  of  all  its  parts,  the  proving  of  the 
pumps,  piping,  etc.,  and  the  charging  of  the  plant  with 
ammonia.  A  working  test  is  also  frequently  made.  For 
the  mounting  the  same  rules  apply  as  in  the  case  of 
other  motive  machinery. 

PROVING  OF  THE  MACHINE. 

In  order  to  prove  a  new  plant,  before  it  is  charged 
with  ammonia  it  should  be  filled  with  compressed  air 
to  a  pressure  of  about  300  pounds.  This  is  done  by 
working  the  compressor,  while  the  suction  valves  pro- 
vided for'  this  purpose  are  opened.  Thick  soap  lather, 
which  is  spread  over  the  pipes,  etc. ,  shows  leaks  by  the 
formation  of  bubbles  under  the  above  pressure.  The 
condenser  and  brine  tanks,  filled  with  water,  show  leaks 
by  the  bubbles  of  air  escaping  through  the  water.  The 
air  pressure  thus  obtained  on  the  system  may  be  used  to 
blow  out  the  pipes,  valves,  etc.  After  a  pressure  is 
pumped  on  the  system,  and  after  the  temperature  is 
equalized  throughout  the  whole  system,  the  pressure 
gauge  ought  to  remain  stationary  if  the  plant  is  abso- 
,lutely  air  tight. 

PUMPING  A  VACUUM. 

If  the  machinery  is  found  to  be  perfectly  air  tight, 
all  the  air  is  discharged  from  the  system  by  opening  the 
proper  valves  and  working  the  pumps.  After  a  vacuum 
has  been  obtained  all  outlets  are  closed,  and  the  con- 
stancy of  the  vacuum  is  observed  on  the  vacuum  gauge 
to  see  if  the  plant  will  withstand  external  pressure. 

CHARGING  THE  PLANT. 

After  the  vacuum  is  shown  to  be  perfect,  the  drum 
with  ammonia  is  connected  to  the  charging  valve.  Before 
opening  the  valve  on  ammonia  flask,  the  expansion  valve 
between  ammonia  receiver  and  expander  is  closed.  Now 
the  liquid  ammonia  is  exhausted  into  the  system,  while 
the  compressor  is  kept  running  at  a  very  slow  speed  with 
suction  and  discharge  valves  opened  and  water  running 
on  the  condenser. 


274  MECHANICAL  REFRIGERATION. 

CHARGING  THE  PLANT  BY  DEGREES. 

If  the  air  is  not  completely  exhausted  from  the  plant, 
i.  e.,  if  the  vacuum  is  not  perfect,  it  is  advisable  to 
charge  the  plant  with  ammonia  by  degrees.  First  about 
one-half  of  the  total  amount  of  ammonia  is  charged,  and 
after  this  has  thoroughly  circulated  in  the  system,  most 
of  the  remaining  air  will  have  collected  in  the  top  of 
condenser,  whence  it  can  be  blown  off  by  a  cock.  After 
this  has  been  done  the  balance  of  the  ammonia  is  charged 
in  a  similar  way  in  one  or  two  additional  installments. 

OPERATION  OF  PLANT. 

The  proper  working  of  a  compression  machine  is 
chiefly  regulated  by  the  amount  of  ammonia  passing 
through  the  same,  which  is  done  by  the  expansion  valve, 
which  must  be  manipulated  very  carefully. 

The  pipe  conveying  the  compressed  ammonia  to  the 
condenser  should  not  get  warm,  and  the  temperature  of 
the  brine  should  be  about  5°  to  10°  F.  higher  than  the 
temperature  corresponding  to  the  indication  of  pressure 
gauge  on  refrigerator. 

The  temperature  of  the  cooling  water  should  be 
about  10°  to  15°  F.  (sometimes  as  much  as  20°)  below  the 
temperature  corresponding  to  the  pressure  in  condenser 
coils. 

The  sound  of  the  liquid  ammonia  passing  the  regu- 
lating valve  should  be  continuous  and  sonorous,  this  in- 
dicating the  absence  of  a  mixture  of  gas  and  liquid. 

DETECTION  OF  LEAKS. 

If  any  ammoniacal  smell  is  discovered  while  charging 
the  plant,  it  is  probably  due  to  leaks,  and  they  should  be 
instantly  located  and  mended.  It  is  of  importance  to 
discover  the  existence  of  a  leak  at  the  first  inception. 
When  in  a  machine  in  operation,  the  liquid  in  the  tanks 
begins  to  smell,  it  shows  either  a  very  considerable  leak 
or  one  of  long  standing,  and  in  order  to  detect  a  leak 
readily  under  those  circumstances  it  is  best  to  test  those 
liquors  regularly  from  time 'to  time  with  Nessler's  solu- 
tion, of  which  a  few  drops  are  added  to  some  of  the  sus- 
pected liquid  in  a  test  tube  or  other  small  glass  vessel,  as 
described  on  page  103. 

MENDING  LEAKS. 

It  is  a  very  efficient  and  simple  method  to  close  small 
leaks  by  soldering  them  up  with  tin  solder,  which  is  fre- 


MANAGEMENT  OF  COMPRESSION  PLANT.  275 

quently  employed  and  gives  general  satisfaction.  The 
soldering  fluid,  in  order  to  properly  clean  the  iron,  should 
contain  some  chloride  of  ammonia,  and  it  is  best  and 
proper  that  its  quantity  should  be  such  as  to  form  a  con- 
siderable proportion  of  a  double  chloride  of  zinc  and  am- 
monia. A  soldering  liquid  of  this  kind  can  be  made  by 
dissolving  in  a  given  amount  of  muriatic  acid  as  much 
zinc  as  it  will  dissolve,  and  to  do  this  in  such  a  manner  as 
to  be  able  to  ascertain  the  weight  of  zinc  that  has  been 
thus  dissolved.  An  amount  of  chloride  of  ammonia  or 
sal  ammoniac  approximately  equal  in  weight  to  that  of 
the  zinc  dissolved  is  then  added  to  the  solution  of  zinc  in 
muriatic  acid. 

If  the  leaks  are  too  large  to  be  mended  in  this  way, 
new  coils  or  new  lengths  of  pipe  must  be  put  in.  In  some 
cases,  where  conditions  are  favorable,  electric  welding 
may  be  resorted  to.  A  cement  made  by  mixing  litharge 
with  glycerine  to  a  stiff  paste  is  also  recommended  for 
closing  leaks.  In  this  case  the  cement  must  be  fortified 
by  the  application  of  sheet  rubber  and  sheet  iron  sleeves 
kept  in  position  by  iron  clasps. 

Generally  the  amount  of  ammonia  is  determined 
after  a  rule  of  thumb  fashion,  allowing  one-third  pound  of 
ammonia  for  every  running  foot  of  2-inch  pipe  (or  its  equiv- 
alent) in  expansion  coils.  Thus  a  plant  of  twenty-five 
tons  ice  making  capacity  having  about  5,000  feet  of  2- 
inch  pipe  would  require  about  5-°s°-°  =  1.666  pounds  of  am- 
monia, while  a  direct  expansion  plant  of  twenty-five  tons 
refrigerating  capacity  having  at  the  rate  of  2,000  feet  of  2- 
inch  pipe  would  require  about  2-°5QO  =  700  pounds  of  am- 
monia. A  machine  of  the  same  capacity  (twenty-five  tons 
refrigeration)  with  brine  circulation  would  require  only 
about  275  pounds  of  ammonia. 

Calculated  for  capacity,  this  would  correspond  to 
about  forty-five  pounds  of  ammonia  per  ton  of  ice  mak- 
ing capacity,  twenty-five  pounds  of  ammonia  per  ton  of 
direct  expansion  refrigerating  capacity  and  twelve  pounds 
of  ammonia  per  ton  of  refrigerating  capacity,  brine  cir- 
culation. These  rules  are  arbitrary,  some  allowing  much 
less  ammonia,  according  to  the  location  of  pipes. 

WASTE  OF  AMMONIA. 

Another  question  of  considerable  interest  to  the 
practical  operators  of  ice  plants  is  in  regard  to  the  waste 


276  MECHANICAL  REFRIGERATION. 

of  ammonia  that  may  be  expected  to  be  incurred. 
Theoretically  speaking,  no  waste  ought  to  take  place,  as 
the  same  quantity  of  ammonia  is  used  over  and  over 
again,  but  in  practice  the  anhydrous  ammonia  gives  way 
in  the  course  of  time.  This  is  due  to  leakage  in  a  great 
measure,  and  partly  also  to  decomposition  of  ammonia. 
The  amount  of  wastage  depends,  of  course,  largely  on  the 
care  with  which  the  plant  is  operated,  and  in  the  absence 
of  any  actual  leakage  is  altogether  due  to  decomposition 
of  ammonia,  which  can  be  obviated  in  a  great  measure  by 
keeping  down  the  temperature  around  the  compressor 
as  much  as  possible.  The  amount  of  ammonia  wasted 
while  a  machine  is  running  depends  almost  entirely  on 
the  care  and  watchfulness,  and  may  run  all  the  way  up 
to  200  pounds  per  year  on  a  plant  of  twenty-five  tons 
capacity.  In  some  cases  it  amounts  to  very  little,  but 
about  fifty  to  100  pounds  is  generally  considered  as  an  un- 
avoidable waste  for  a  25-ton  machine.  Where  there  is  a 
liquid  receiver  provided  with  a  gauge  glass,  the  attend- 
ant can  readily  tell  when  the  ammonia  is  running  low  in 
the  machine.  Otherwise  the  insufficiency  of  ammonia 
is  shown  by  a  fluctuating  pressure,  variation  in  the  tem- 
perature of  the  discharge  pipe,  and  by  the  running  of  the 
valves  in  the  compressor,  which  sometimes  run  smooth 
and  easy,  and  at  other  times  hard,  showing  that  the  sup- 
ply of  ammonia  and  the  consequent  resistance  varies. 

A  rattling  noise  of  the  liquid  while  passing  the  ex- 
pansion valve  shows  the  passage  of  vapor  along  with  the 
liquid  ammonia,  and  proves  that  the  ammonia  in  the 
system  is  deficient. 

AMMONIA  IN  CASE  OF  FIRE. 

It  appears  that  the  dangers  of  ammonia  in  case  of  fire 
have  been  greatly  over-rated,  and  at  least  in  the  begin- 
ning of  a  fire  it  acts  as  an  extinguisher  rather  than  other- 
wise. For  this  reason  it  seems  more  advisable  in  case  of 
fire  to  allow  the  ammonia  to  escape  whenever  it  is  deemed 
good  policy  to  stand  the  loss  of  the"  ammonia  rather  than 
run  the  risk  of  fire.  If  the  latter  happened  the  am- 
monia would  be  lost  anyhow,  and  that,  too,  most  likely, 
at  a  temperature  high  enough  to  make  it  share  in 
the  conflagration,  while  when  allowed  to  escape,  as  long 
as  the  fire  is  low  it  may  help  to  stifle  the  same  or  extin- 
guish it  altogether. 


MANAGEMENT  OF  COMPRESSION  PLANT.  277 

Before  resorting  to  such  an  expedient  the  pros  and 
cons  should,  of  course,  be  duly  considered,  and  the  at- 
tendant should  properly  protect  himself  by  a  mask  or 
similar  contrivance  against  the  suffocating  effect  of  the 
ammonia  vapors  to  which  he  may  be  exposed  while  pro- 
viding means  for  their  escape  in  the  free  atmosphere.  In 
order  to  further  provide  for  such  an  emergency,  the  out- 
let valve  at  the  lower  end  of  the  condenser  should  be 
conveniently  located,  as  the  liquid  ammonia  should  be 
permitted  to  escape  first.  While  countenancing  such 
heroic  measures,  I  will  not  dispute  that  under  certain 
conditions  decomposing  ammonia  may,  through  ignition, 
also  become  the  cause  of  fire.  When,  for  instance,  the 
head  of  a  compressor  running  very  hot  should  be  blown 
off , the  escaping  hot  ammonia,especially  if  saturated  with 
lubricating  oil,  may  be  in  a  condition  prone  to  decompose, 
and  in  case  these  vapors  should  come  in  contact  with  the 
flame  of  a  light,  the  fire  under  the  boiler,  or  a  lighted 
match,  a  flash  of  fire  might  take  place, which  amid  the  con- 
fusion generally  attending  an  accident  of  this  kind  might 
give  rise  to  a  destructive  conflagration.  In  view  of  this 
possibility,  it  has  been  recommended  that  the  lamps  in 
the  engine  room  of  a  refrigerating  plant  should  be  pro- 
tected by  a  fine  wire  screen,  that  the  doors  leading  to  the 
boiler  door  should  be  likewise  made  of  fine  wire  cloth  and 
be  provided  with  a  reliable  self-closing  contrivance.  The 
lighting  of  matches,  etc.,  should  be  avoided  in  the  engine 
room  for  the  same  reason. 

CONDENSER  AND  BACK  PRESSURE. 

The  lower  the  pressure  and  temperature  in  condenser 
coil,  and  the  higher  the  pressure  and  temperature  in  ex- 
panding coil  (back  pressure),  the  more  economical  will  be 
the  working  of  the  plant.  This  is  readily  apparent  from 
the  formulae  given  for  the  estimation  of  the  compressor 
capacity;  it  is  even  more  readily  apparent  from  the  sub- 
joined tables,  showing  the  actual  result  obtained  by 
Schroeter  in  working  an  anhydrous  ammonia  compressor 
under  different  conditions.  For  these  reasons  the  cooling 
water  on  the  condenser  should  be  used  as  cold  as  it  can 
be  had  and  in  as  ample  profusion  as  possible.  Likewise 
the  expansion  or  back  pressure  should  be  held  as  high 
as  possible. 

In  brewery  refrigeration,  cold  storage  and  other  es- 
tablishments in  which  the  temperature  is  to  be  kept  at 


278 


MECHANICAL  REFRIGERATION. 


32°  F.,  or  thereabouts,  by  direct  expansion,  a  back  press- 
ure of  about  33  pounds  gauge  pressure,  corresponding  to 
about  20°  P.,  is  generally  maintained. 

In  case  brine  circulation  is  used  for  above  purposes, 
the  brine  returns  with  a  temperature  of  24  to  26°  F.  and 
enters  the  room  with  a  temperature  of  about  20°.  The 
back  pressure  in  ammonia  coils  in  this  case  is  25  to  28 
pounds,  corresponding  to  a  temperature  of  10  to  15°  F. 

During  the  chilling  stage  in  meat  or  other  cold  stor- 
age, the  temperature  in  the  room  rises  in  the  beginning 
to  5(P,  and  a  higher  back  pressure— about  60  pounds, 
corresponding  to  a  temperature  of  about  40°  in  ammonia 
coil— is  maintained.  Gradually,  as  the  temperature  falls  in 
the  room,  the  back  pressure  also  decreases  until  it 
reaches  the  point  corresponding  to  the  temperature  'of 
the  room  for  cold  storage,  viz.,  about  30  pounds. 

In  freezing  meat,  for  which  purpose  temperatures  of 
0°  F.  and  below  in  rooms  are  required,  the  back  press- 
ure gets  as  low  as  4  pounds, corresponding  to  a  temperature 
of—  20°  F. 

For  ice  making  a  temperature  of  10°  to  20°  is  main- 
tained in  the  brine,  and  the  back  pressure  in  ammonia 
coils  in  this  case  is  from  20  to  28  pounds,  corresponding 
to  a  temperature  of  5°  to  15°  F. 

TABLE    SHOWING  EFFICIENCY  OF  PLANT  UNDER  DIFFER- 
ENT CONDITIONS. 


N  o.  of  test  

1 

2 

3 

1 

Temperature  of  )  ?„]„+  ^otr  ™ 
refrigerated     |8S8S8»jr 

Specific  heat  of  brine  (per  unit 
of  volume),  

43.194 
37.054 

0.8608 

28.344 

22.885 

0.8508 

13.952 

8.771 

0.8427 

-0.279 
-5.879 

0.8374 

Quantity  of  brine  circulated  per 
hour  cu    ft 

1,039.38 

908.84 

633.89 

414.98 

Cold  produced;B.  T.  U.  per  hour 
Temperature  1  r  }  t  d       F 

W^JS^S 

342.909 
48.832 
66.724 

263.950 
49.476 
68.013 

172.776 
48.931 
67.282 

121.474 

49.098 
67.267 

condenser,     j 
Quantity  of  cooling  water  per 
hour  in  cu.  ft 

338  .  76 

260.83 

187.506 

139.99 

Heat  eliminated  by  condenser, 
B.  T  U    per  hour 

378.358 

301.404 

214.796 

158.926 

I.  H.  P.  in  compressor  cylinder. 
I.  H.  P.  in  steam  engine  cylinder 
Consumption  of  steam  per  hour 
in  Ibs... 

13.82 
15.80 

311  51 

14.29 
16.47 

335  98 

13.53 
15.28 

i05.S7 

11.98 
14.24 

278.79 

1  Per  I.  H.  P.  in 
Cold  produced       comp.  cyl  
$er  hour,  B.     Per  I.  H.  P.  in 
.  U.                    steam  cyl  
Per  Ib.  of  steam 

24.813 

21.703 
1,100.8 

18.471 

16.026 

"85.6 

12.770 

11.307 

564.9 

10.140 

8.530 
435.82 

MANAGEMENT  OF  COMPRESSION  PLANT.  279 

PERMANENT  GASES  IN  PLANT. 

As  long  as  their  amount  is  small  and  as  long  as  there 
is  sufficient  liquid  in  the  condenser  coil  to  act  as  a  seal 
preventing  the  free  circulation  of  the  permanent  gases 
in  the  system,  their  presence  will  only  decrease  the 
capacity  of  the  condenser  coil,  as  it  were,  requiring  either 
a  little  more  cooling  water  or  increase  the  pressure  in  the 
condenser.  If  these  gases  are  present  in  larger  quantity, 
and  especially  when  there  is  no  excess  of  liquid  ammonia  in 
condenser  coils,  they  will  disseminate  themselves  through 
the  whole  plant  and  interfere  both  with  the  economical 
working  of  the  plant  and  the  correct  indications  of  the 
gauges,  etc.  For  these  reasons  the  engineers  ought  to 
be  watchful  to  prevent  any  accumulation  of  such  gases. 
Sometimes  they  consist  chiefly  of  atmospheric  air,  but 
sometimes  also  of  hydrogen  and  nitrogen,  due  to  the 
decomposition  of  ammonia.  The  best  way  to  remove  these 
gases  from  the  system  is  by  drawing  them  off  at  the  top 
of  the  condenser  coil.  It  is  advisable  when  drawing  off 
the  permanent  gases  to  make  the  condenser  as  cold  as 
possible  by  using  an  excess  of  cooling  water  and  by  stop- 
ping the  inflow  of  ammonia  gas  to  the  condenser  for  the 
time  being.  A  small  hose,  or,  better  still,  a  permanent 
small  pipe,  may  be  attached  to  the  top  of  the  condenser 
or  provided  with  a  valve  near  the  condenser,  the  other 
end  dipping  in  cold  water.  If  on  opening  the  valve 
bubbles  are  seen  to  escape  through  the  water  the  valve 
should  be  kept  open  as  long  as  such  bubbles  appear  in 
the  water.  If,  however,  the  bubbles  cease  to  appear  in 
noticeable  quantity,  while  a  crackling  noise  in  the  water 
indicates  that  most  of  the  gas  escaping  through  the  pipe 
is  ammonia,  which  is  absorbed  by  the  water,  then  the 
valve  should  be  closed,  as  all  the  permanent  gases  that 
can  be  removed  at  the  time  without  undue  loss  of  am- 
monia have  been  disposed  of,  at  least  for  the  time  being. 

FREEZING  BACK. 

The  tendency  of  freezing  back  shown  by  certain  ma- 
chines and  not  by  others,  is  explained  by  their  mode  of 
working.  The  former  machines  work  by  what  is  called 
the  method  of  wet  compression,  and  the  others  by  the 
method  of  dry  compression.  The  tendency  to  freeze 
back  itself  involves  no  loss,  for  a>  machine  intended  for 
wet  compression  may  also  be  worked  with  dry  gas,  by 


280  MECHANICAL  REFRIGERATION. 

opening  the  expansion  valve  very  little,  but  in  doing  so 
the  capacity  of  the  machine  is  reduced  and  the  power 
required  to  work  the  compressor  is  increased. 

PRACTICE  IN  WET  COMPRESSION. 

In  working  with  wet  expansion  the  object  is  to 
deliver  the  gas  from  the  compressor  in  a  saturated  con- 
dition, but  if  this  were  actually  done  we  would  never  be 
sure  that  certain  amounts  of  liquid  were  not  mixed 
with  the  gas,  which  would  constitute  a  severe  loss.  For 
this  reason  it  is  indicated  to  allow  the  temperature  of 
the  vapor  leaving  the  compressor  to  be  about  20°  above 
that  of  the  liquid  leaving  the  condenser.  Inattention 
to  this  point  probably  accounts  for  many  differences  of 
opinion  in  regard  to  dry  and  wet  compression.  Any 
liquid  present  under  such  conditions  would  fill  the  clear- 
ance space,  and  by  expanding  would  destroy  a  corre- 
sponding percentage  of  compressor  capacity  (^-inch 
clearance  filled  with  liquid  ammonia  would  reduce  the 
capacity  over  one-third). 

ORIGIN  OF  PERMANENT  GASES. 

In  the  operation  of  a  compression  plant  the  undue 
heating  of  the  gas  during  compression  must  be  consid- 
ered as  the  chief  cause  for  the  decomposition  of  am- 
monia and  the  origination  of  permanent  gases.  How- 
ever, it  also  frequently  happens  that  air  is  drawn  into 
the  system  through  leaks,  in  case  a  vacuum  has  been 
pumped,  which  some  engineers  are  unnecessarily  in  the 
habit  of  doing  whenever  they  stop  the  plant  for  a  length 
of  time. 

CLEARANCE  MARKS. 

The  clearance  in  the  compressor  is  not  a  fixed  quan- 
tity, but  changes  with  the  natural  wear  of  cranks  and 
cross-head.  For  this  reason  clearance  marks  should  be 
provided  for  on  the  guides  and  cross-heads  of  compressors 
as  well  as  engine.  These  will  indicate  if  the  clearance 
is  equalized  at  the  end  of  cylinders,  and  guide  us  in  the 
matter  of  keying  up  the  bearings.  The  clearance  should 
not  exceed  &  part  of  an  inch. 

VALVE  LIFT. 

The  lift  of  compressor  valves  must  be  carefully  ad- 
justed to  the  speed  of  piston  (to  get  full  discharge),  sup- 
ply of  condenser  water,  etc. 


MANAGEMENT  OF  COMPRESSION  PLANT.  281 

If  valves  are  not  properly  set  and  cushioned  they 
pound,  which  may  even  cause  the  texture  of  the  metal 
to  change  in  such  a  way  as  to  cause  their  breaking  to 
pieces. 

PACKING  OF  COMPRESSOR  PISTON. 

If  the  piston  rod  is  of  uniform  diameter  and  well 
polished,  the  packing  will  last  several  months,  other- 
wise it  may  have  to  be  renewed  every  month. 

If  the  compressor  valves  or  pistons  should  leak,  the 
refrigerator  pressure  will  rise  and  the  condenser  pressure 
will  fall. 

When  it  becomes  necessary  to  open  any  part  of  the 
plant  the  ammonia  should  be  transferred  to  another 
part,  or  if  this  is  impracticable  it  should  be  removed  by 
absorption  in  water. 

POUNDING  PUMPS  AND  ENGINES. 

Sounds  that  appear  to  proceed  from  first  one  place 
and  then  another  about  the  engine  and  pumps  can  gener- 
ally be  located  by  the  use  of  a  piece  of  rubber  tubing, 
one  end  of  which  is  held  to  the  ear  while  the  other  end  is 
brought  close  to  the  suspected  place.  The  opposite  ear 
should  be  closed  to  shut  out  the  sound. 

An  old  yet  very  effective  way  to  locate  any  noise  in- 
side of  an  engine  or  pump  cylinder  is  to  place  one  end  of 
a  wrench  or  other  piece  of  metal  between  the  teeth,  and 
resting  the  other  end  on  the  cylinder  head,  close  both 
ears.  Every  sound  within  the  cylinder  can  thus  be 
readily  heard. 

CLEANING  CONDENSER. 

If  the  condenser  coils  have  a  tendency  to  become 
incrusted  by  deposit  from  the  water,  they  should  be 
cleaned  from  time  to  time.  On  such  occasions  they  may 
also  be  tested  with  a  water  pressure  of  some  400  pounds 
per  square  inch  to  discover  corrosion,  perforation  and 
other  bad  places. 

CLEANING  COILS,  ETC.,  FROM  OIL. 

If  there  is  oil  in  parts  of  the  system  whence  it 
cannot  be  removed  by  the  oil  traps,  those  parts  may  be 
blown  out,  and  if  consisting  of  pipe  they  can  be  blown 
out  by  sections,  if  practicable.  Another  way  more 
strongly  recommended,  and  more  simple,  to  clean  am- 
monia pipes  from  oil,  consists  in  allowing  high  pressure 
ammonia  gas  to  enter  them;  this  warms  and  liquefies  the 


282  MECHANICAL  REFRIGERATION. 

oil  sufficiently  to  permit  of  its  being  drawn  (mixed  with  the 
ammonia)  into  the  compressor,  whence  it  passes  to  the 
oil  traps,  where  it  is  separated  from  the  ammonia.  This 
method  of  cleaning  the  coils  is  said  to  be  very  effective 
if  repeated  from  time  to  time,  say  once  a  week,  or  better 
still,  every  other  day. 

INSULATION. 

The  most  important  point  in  the  economical  running 
of  a  plant  is  insulation,  and  especially  does  this  refer  to 
the  ammonia  on  its  way  from  the  refrigerator  to  the 
compressor,  and  from  the  condenser  to  the  refrigerator 
through  the  liquid  receiver,  etc.  For  these  reasons  these 
conduits  cannot  be  insulated  too  well.  The  same  applies 
to  brine  tank,  freezing  tank,  etc. 

PAINTING  BRINE  TANKS,  ETC. 

Light  colored  surfaces  radiate  and  absorb  less  heat 
than  dark  surfaces  under  the  same  conditions.  Also 
smooth  and  bright  surfaces  will  radiate  and  absorb  less 
heat  than  rough  and  dead  looking  surfaces  of  the  same 
color.  That  the  differences  in  radiation  brought  about 
in  this  way  are  great  enough  to  be  quite  observable 
about  a  refrigeration  plant,  for  instance,  on  the  efficiency 
of  a  brine  tank  or  other  vats,  we  make  no  ttoubt.  For 
this  reason  light  colors,  possibly  white,  and  smoothly 
varnished  at  that,  are,  doubtless,  best  adapted  to  all  sur- 
faces. Preferably  a  white  earthy  paint,  like  barytes, 
etc.,  but  no  white  lead,  should  be  used  for  this  purpose, 

LUBRICATION. 

The  oil  used  for  lubricating  the  compressor  differs 
from  ordinary  lubricating  oil  in  that  it  must  not  congeal 
at  low  temperature,  and  must  be  free  from  vegetable  or 
animal  oils.  For  this  reason  only  mineral  oils  can  be 
used,  and  of  these  only  such  as  will  stand  a  low  tempera- 
ture without  freezing,  such  as  the  best  paraffine  oil,  will 
do.  Regular  cylinder  oil,  however,  should  be  used  for 
the  steam  cylinder,  and  a  free  flowing  oil  of  sufficient 
body  for  all  bearings  and  other  wearing  surfaces. 

For  heavy  bearings  on  ice  machines  a  heavy  oil 
should  be  used,  while  small  bearings,  such  as  shafts  of 
dynamos,  should  be  lubricated  by  a  very  light  oil,  to 
avoid  undue  heating  in  either  case.  Graphite  or  black 
lead  is  also  an  efficient  lubricant. 


MANAGEMENT  OF  ABSORPTION  PLANT.  283 

CHAPTER    XV.— MANAGEMENT     OF     ABSORP- 
TION PLANT. 

MANAGEMENT  OF  ABSORPTION  MACHINE. 

The  management  of  an  ammonia  absorption  plant 
has  many  points  in  common  with  that  of  a  compression 
plant.  The  detection  and  mending  of  leaks,  lubrication, 
the  management  of  ammonia,  withdrawal  of  permanent 
gas,  etc.,  are  the  same  in  both,  and  they  have  been  en- 
larged upon  in  the  foregoing.  There  are,  however,  many 
precautions  and  troubles  peculiar  to  the  absorption  sys- 
tem, and  the  most  important  of  them  will  be  shortly 
mentioned  hereafter,  and  some  of  these  in  turn  will  also 
apply  to  the  operation  of  the  compression  plant. 

INSTALLATION   OF  ABSORPTION  PLANT. 

The  installation  and  testing  of  an  ammonia  absorp 
tion  plant  is  generally  attended  to  by  the  manufacturers. 
The  plant  before  being  put  in  operation  should  be  tested 
to  a  pressure  of  about  300  pounds  per  square  inch. 

CHARGING  ABSORPTION  PLANT. 

Before  the  ammonia  is  charged  into  the  machine,  it 
is  necessary  to  expel  from  the  entire  apparatus  the  air 
which  it  naturally  contains. 

There  are  two  methods  of  doing  this,  one  of  which 
consists  in  opening  all  the  connecting  valves  in  the 
machine;  leave  one  open  to  the  atmosphere,  introduce 
direct  steam  in  the  retort  until  all  the  air  is  forced  out, 
and  then  shut  the  outlet  valve  and  let  the  apparatus  cool 
off.  When  it  becomes  cold,  there  will  be  found  to  be  a 
vacuum  in  the  whole  apparatus.  It  is  then  ready  to 
receive  the  ammonia.  This  method,  however,  is  not  to 
be  recommended,  as  the  heat  of  the  steam  will  soften 
the  joints,  especially  if  rubber  is  used. 

The  best  way  is  to  pump  a  vacuum  by  means  of  a 
good  pump.  The  boiler  feed  pump  or  the  ammonia  pump 
may  be  used  for  this  purpose,  and  when  a  vacuum  of 
twenty-five  inches  is  obtained,  close  all  the  valves.  Then 
connect  the  charge  pipe  with  the  drum  of  aqua  ammonia, 
taking  care  not  to  let  any  air  enter  the  pipe  after  the 
drum  is  empty.  Close  the  charge  valve  and  repeat  the 
operation  with  another  drum,  until  the  vacuum  in  the 
machine  is  gone,  and  then  pump  in  the  balance  with  the 
ammonia  pump  until  nearly  the  requisite  charge  is  put 
in;  then  heat  the  ammonia  slowly  by  turning  steam 
through  the  heater  coils.  When  the  pressure  gauge 


284  MECHANICAL  REFRIGERATION. 

indicates  100  pounds,  more  or  less,  open  the  purge  cock 
and  lead  the  discharge  into  a  pail  of  cold  water  through 
a  rubber  tube  until  no  air  bubbles  come  out*,  then  turn 
on  the  condensing  water  into  the  condenser  cooler  and 
absorber,  and  apply  the  steam  until  the  liquefied  gas 
shows  in  glass  gauge.  Then  open  distributing  valve  to 
freezing  tank,  and  turn  the  poor  liquor  into  absorber, 
and  in  a  few  minutes  the  ammonia  pump  may  be  started 
to  pump  the  enriched  liquor  through  the  coils  of  ex- 
changer and  into  the  retort.  Let  the  condensed  steam 
into  the  deaerator  and  let  cooling  water  run  over  the 
distilled  water  cooler  coils.  Let  it  run  out  until  the 
water  becomes  clear  and  tasteless.  Proceed  in  this  way, 
carefully  watching  for  ammonia  leaks  wherever  there 
are  joints.  If  none  exist,  keep  on  until  all  the  pipes  in 
the  freezing  tank  become  coated  with  frost,  and  the 
remaining  air  has  consequently  been  driven  out  through 
the  coils  and  out  of  the  absorber  purger.  Then  close 
down  and  proceed  and  make  the  brine  solution,  when 
the  machine  is  ready  to  start  again  and  the  balance  of 
the  ammonia  may  be  put  into  the  machine  and  operated 
in  the  regular  manner. 

OVERCHARGE  OF  PLANT. 

In  charging  an  absorption  machine  with,  ammonia 
liquor,  which  is  generally  done  when  it  is  cold,  it  should 
be  borne  in  mind  that  the  liquid  expands  when  heat  is 
applied,  and  that  if  the  machine  is  charged  to  its  work- 
ing point  when  cold,  it  will  invariably  be  overcharged 
under  working  conditions.  In  such  a  case  the  liquor 
may  go  out  of  sight  in  the  gauge  and  great  variations  of 
pressure  take  place,  which  are  apt  to  damage  the  recti- 
fying pans,  and  the  proportionate  strengths  of  poor  and 
rich  liquor  are  disturbed. 

AMMONIA  REQUIRED. 

When  the  regular  automatic  operation  of  the  absorp- 
tion cycle  has  been  inaugurated,  a  surplus  of  liquid  am- 
monia should  show  itself  in  the  liquid  receiver.  If  there 
is  a  deficiency  in  this  respect  it  can  be  supplied  by  the  ad- 
dition of  anhydrous  ammonia,  or  by  the  addition  of  strong 
ammonia  liquor,  and  the  withdrawal  of  a  corresponding 
amount  of  weak  liquor.  The  sound  of  the  liquor  passing 
the  expansion  valve  should  be  continuous  and  sonorous, 
as  in  the  case  of  the  compression  machine,  indicating  the 
absence  of  a  mixture  of  gas  and  liquid. 


MANAGEMENT  OF  ABSORPTION  PLANT.  285 

RECHARGING  ABSORPTION  PLANT. 

For  the  purpose  of  recharging  an  absorption  plant 
De  Coppet  gives  the  following  rational  directions:  When 
the  gas  has  leaked  out  or  the  liquor  has  become  impov- 
erished, and  knowing  the  original  charge  by  weight  and 
density,  as  for  instance,  say  the  original  charge  was  4,000 
pounds  at  26°  B.,  there  would  be  1,040  pounds  of  am- 
monia in  2,960  of  water;  if  the  density  through  leakage  or 
purging  came  down  to  say  23°,  there  would  be  a  loss  of 
120  pounds  in  the  original  charge,  which  can  be  easily  sup- 
plied by  placing  a  drum  of  anhydrous  ammonia  on  a 
scale,  taking  a  long  and  small  flexible  pipe,  say  a  half 
inch,  connected  between  the  drum  and  same  part  of  the 
machine,  say  the  feed  pipe  to  freezing  tank,  weigh  the 
drum  accurately  before  opening  the  valve,  let  the  liquid 
gas  run  in  the  machine  until  there  are  within  a  few 
pounds  of  the  quantity  missing;  run  out  of  the  cylinder 
into  the  machine,  say  ten  or  fifteen  pounds,  then  close 
the  cylinder  valve  and  try  the  machine  by  running  it  in 
the  usual  way  for  an  hour  or  two.  Then  add  the  ten  or 
fifteen  pounds  extra,  and  if  all  the  air  has  been  blown 
out  of  the  tube,  and  if  the  ammonia  is  pure,  his  machine 
will  work  all  right  again.  When  the  liquor  is  lacking  it 
is  best  to  recharge  the  machine  with  strong  aqua  at  26° 
to  28°  until  the  original  level  is  reached,  which  can  easily 
be  ascertained  if  a  glass  level  or  test  cock  has  been 
placed  on  the  generator  or  still.  He  has  adopted  this 
method  for  fifteen  years,  and  finds  it  far  preferable  to 
that  of  concentrating  the  liquid  and  recharging  it  with 
rich  ammonia  afterward,  securing  the  same  amount  of 
poor  liquor,  besides  saving  time  and  money. 

When  the  question  presents  itself  as  to  how  much 
anhydrous  ammonia,  as,  in  pounds  must  be  added  to  m 
pounds  of  ammonia  liquor  of  the  percentage  strength  a 
in  order  to  convert  it  into  ammonia  liquor  of  the  per- 
centage strength  6,  it  may  be  readily  answered  after 
the  following  formula: 


100-6 

CHARGING  WITH  RICH  LIQUOR. 

When  the  absorption  system  is  charged  with  strong 
aqua  ammonia  it  happens  sometimes  that  the  pump  will 
not  readily  take  the  strong  liquor.  This  is  due  to  the  great 
tension  of  the  ammonia  in  the  strong  solution,  which 


286  MECHAKiOAL  REFRIGERATION. 

fills  the  pump  up  with  ammonia  vapor  in  such  a  way 
that  the  liquid  cannot  be  drawn  in.  The  same  thing  fre- 
quently happens  with  boiler  feed  pumps,  when-  the  feed 
water  becomes  nearly  boiling  hot.  Generally  it  is  found 
that  in  such  cases  the  pump  stands  too  high;  if  it  stands 
below  the  liquid  to  be  pumped  the  latter  will  fill  the 
pump  in  preference  to  the  vapor,  and  the  pump  will  gen- 
erally work  all  right. 

It  should  be  noticed,  however,  that  this  artifice  of 
elevating  the  receptacle  containing  the  rich  liquor  above 
the  pump  will  only  be  efficient  if  it  is  done  in  such  a 
manner  that  the  liquid  will  run  into  and  fill  the  pump 
by  its  own  gravity.  If  the  liquid  has  to  be  syphoned 
over  by  the  pump,  it  will  make  little  difference  whether 
the  pump  stands  a  little  above  or  below  the  liquor,  as  in 
either  case  the  vapor  of  the  rich  liquor  will  fill  the  syphon 
and  pump  in  preference  to  the  liquid  if  the  pump  is  not 
in  first-class  working  order.  This  tendency  is  increased 
when  the  pump  is  allowed  to  run  dry  and  hot  on  starting, 
and  for  this  reason  the  cooling  of  the  pump  with  water 
frequently  remedies  the  trouble.  This,  the  cooling  of  the 
pump,  so  it  will  take  the  rich  liquor,  may  be  accomplished 
according  to  a  practical  operator  by  stopping  the  pump, 
while  the  machine  otherwise  is  running  as  usual.  In  this 
way  the  absorber  is  cooled  down  in  a  short  time ;  mean- 
while the  drum  containing  the  rich  liquor  has  also  been 
connected  with  the  pump  which  is  now  started  first  to 
pump  cold  liquor  from  the  absorber  for  a  few  seconds 
when  the  absorber  valve  is  closed  and  the  pump  started 
on  the  rich  liquor,  which  will  then  be  taken  readily.  If 
not  the  procedure  may  be  repeated  once  or  twice. 

PERMANENT  GASES  IN  ABSORPTION  PLANT. 

The  permanent  gases  in  the  absorption  plant  may  be 
due  to  decomposition  of  ammonia  and  also  air  which  has 
found  its  way  into  the  system.  It  appears,  however,  that 
the  decomposition  of  water  vapor  in  the  presence  of  iron 
(and  probably  iron  containing  carbon  in  a  greater  quantity 
or  in  a  more  dissolvable  form  than  other  iron)  is  largely 
responsible  for  their  presence.  The  carbon  which  is  pres- 
ent in  all  iron  may  also  combine  with  hydrogen,  forming 
carburetted  hydrogen.  That  the  nature  of  the  iron  of 
still  and  condenser  worms  has  some  influence  in  this 
direction  is  proven  by  the  fact  that  some  plants  are 


MANAGEMENT  OF  ABSORPTION  PLANT.  287 

much  more  damaged  by  these  corroding  influences  than 
others.  This  difference  in  behavior  must  be  attributed 
to  the  iron  rather  than  to  the  ammonia. 

CORROSION  OF  COILS. 

As  may  be  inferred  from  the  foregoing  paragraph,  it 
will  not  only  be  the  permanent  gases,  thus  found,  which 
annoy  the  manufacturer,  but  also  the  corrosion  and  con- 
sequent destruction  of  the  coils  and  tanks.  This  is,  in- 
deed, the  case  especially  in  the  upper  regions  of  ammonia 
still  and  in  the  condenser.  As  a  precautionary  measure 
it  is  well  to  have  the  coil  in  the  still  always  covered  with 
liquid. 

ECONOMIZING  CONDENSER  COILS. 

As  has  been  stated,  the  iron  of  the  coil  or  worm  in 
condenser  and  in  the  ammonia  still  suffers  much  from 
pitting  and  corrosion,  especially  if  the  liquid  does  not  al- 
ways stand  above  the  coil  in  the  still.  Coddington  finds 
that  the  pitting  takes  place  first  at  the  top  of  the  coils, 
and  therefore  he  has  found  it  a  good  practice  to  turn  the 
condenser  coil  over  after  a  certain  period,  say  after  it  has 
been  used  about  four  years. 

KINDS  OF  AQUA  AMMONIA. 

The  difference  between  the  different  kinds  of  aqua 
ammonia  in  the  market  is  only  in  strength  and  price, 
the  latter  differing  like  that  of  other  commodities, 
according  to  the  law  of  demand  and  supply.  _  At  present 
we  find  in  the  market  (according  to  Beaume  hydrometer 
scale  for  liquids  lighter  than  water,  the  latter  showing 
10°): 

1.  16°  aqua  ammonia,  often  called   by   druggists 
F.  F.  F.,  containing  a  little  more  than  10  per  cent  of 
pure  anhydrous  ammonia. 

2.  18°  aqua  ammonia,  called  by  druggists  F.  F.  F.F., 
containing  nearly  14  per  cent  of  anhydrous  ammonia. 

3.  26°  aqua  ammonia,  called  by  druggists  stronger 
aqua  ammonia,  and  containing  29^  per  cent  of  pure 
anhydrous  ammonia.    This  is  the  aqua  ammonia  gener- 
ally used  in  absorption  plants  for  the  start.    At  last 
quoting  the  prices  (in  carboys)  were  about  two  and  one- 
half  cents  per  pound  for  the  16°,  three  and  one-half  cents 
per  pound  for  the  18°  and  four  and  three-quarters  cents 
per  pound  for  the  26°,  the  latter  not  in  carboys,  but  in 
iron  drums. 


288  MECHANICAL  REFRIGERATION. 

It  is  also  frequently  supposed  that  a  difference  in 
the  nature  of  ammonia  is  due  to  the  different  sources 
from  which  it  is  derived,  viz.,  from  gas  liquor  direct,  or 
from  intermediate  sulphate  of  soda,  but  manufacturers 
claim,  and  with  apparent  reason,  that  this  is  not  the 
case  if  both  kinds  are  equally  well  purified. 

LEAKS  IN  ABSORPTION  PLANT. 

If,  while  the  pump  and  generator  appear  to  work 
regularly,  there  is  a  great  disproportion  in  the  strength  of 
the  poor  and  the  rich  liquor,  so  that  the  strength  of  the 
former  to  the  latter  is  22  to  25,  where  it  should  be  17  to 
28,  or  thereabouts,  it  is  likely  due  to  some  leaks,  more 
particularly  in  the. exchanger  or  equalizer  or  in  the  recti- 
fying pans. 

LEAK  IN  EXCHANGER. 

If  there  is  a  leak  in  the  equalizer  coil  large  enough 
to  seriously  affect  the  working  of  the  machine,  the  pipe 
connecting  the  equalizer  and  the  coil  in  the  weak  liquor 
tank  will  become  cool  when  the  pump  is  running  fast, 
and  the  equalizer  will  be  cool  back  to  a  short  distance 
from  the  leak,  where  the  cold  ammonia  from  the  absorber 
mingles  with  the  weak  liquor  from  the  generator.  And 
at  times,  when  the  pump  is  running  very  fast,  the  whole 
weak  liquor  line  may  cool  back  to  within  a  few  inches  of 
the  generator,  showing  that  strong  ammonia  is  being 
pumped  into  the  bottom  and  top  of  generator,  as  well  as 
into  absorber.  There  will  also  be  a  ringing  or  hissing 
noise  in  the  neighborhood  of  the  leak.  First  locate  the 
trouble  in  the  equalizer  by  noticing  the  cooling  of  the 
pipes,  and  then  find  the  place  in  the  equalizer  by  feeling 
the  different  sections  with  the  pump  running  slower, 
having  also  the  assistance  of  an  ear  tube. 

Another  way  to  try  an  exchanger  coil  while  the 
machine  is  running  is  as  follows:  Close  poor  liquor  valve 
between  the  generator  and  exchanger;  close  absorber 
poor  liquor  feed,  and  run  pump  as  slow  as  possible;  open 
the  poor  liquor  feed  wide;  if  there  is  a  leak,  the  pump 
will  start  faster.  When  the  poor  liquor  feed  is  closed 
at  the  absorber  and  between  retort  and  exchanger,  the 
pump  is  working  against  the  generator's  pressure,  while 
when  the  absorber  feed  is  wide  open  the  pump  is  work- 
ing against  a  lower  pressure  (ten  pounds  per  square  inch) 
through  the  leaky  coil  of  the  exchanger,  then  to  the 
absorber,  thus  forcing  a  by-pass  circulation  of  rich  or 


MANAGEMENT   OF  ABSORPTION  PLANT.  289 

enriched  poor  liquor  from  the  absorber  through  the 
exchanger,  through  the  leak  of  the  coil  of  the  exchanger, 
back  through  the  poor  liquid  cooler  and  to  the  absorber 
again.  If  the  leak  in  the  coil  is  of  a  large  size,  the 
machine  will  come  to  a  standstill,  and  will  stay  that  way 
until  the  leaky  coil  is  not  removed. 

LEAK  IN  RECTIFYING  PANS. 

If  under  existing  regularities  in  the  relative  strength 
of  the  poor  and  rich  liquor  the  exchanger  has  not  been 
found  leaking,  but  perfect  in  its  working,  it  is  almost 
beyond  doubt  that  the  rectifying  pans  are  out  of  order. 
In  order  to  make  sure  on  this  point  a  certain  small 
quantity  of  the  liquefied  ammonia  may  be  withdrawn 
from  the  liquid  receiver,  and  then  be  allowed  to  evapo- 
rate (the  vessel  containing  the  ammonia  being  placed  in 
ice  water).  If  under  these  conditions  a  remnant  (water) 
amounting  to  20  per  cent  and  more  is  shown,  then  there 
is  doubtless  a  leak  in  the  rectifying  pans,  which  should 
be  repaired. 

STRONG  LIQUOR  SYPHONED  OVER. 

When  the  ammonia  is  short  in  a  machine  the 
same  may  be  absorbed  so  quickly  in  the  absorber  as  to 
cause  the  contents  of  the  still  to  be  syphoned  or  drawn 
over  in  the  absorber  and  (if  not  guarded  against  by  check 
valve)  into  the  refrigerator.  Defective  action  of  the  am- 
monia pump  may  cause  the  same  trouble.  For  this  rea- 
son the  gauge  at  still  must  be  closely  watched,  so  that 
the  liquor  always  covers  the  steam  coil,  by  which  an  un- 
due decomposition  of  the  ammonia  and  formation  of  per- 
manent gases  is  also  avoided. 

This  siphoning  over  of  the  ammonia  from  one  part  of 
the  system,  and  absorption  into  another  where  it  does 
not  belong,  is  frequently  called  a  "boil-over  ";  and  besides 
the  siphoning  over  of  the  liquid  to  the  absorber,  etc., 
it  sometimes  happens,  also,  that  the  liquid  runs  over 
from  the  generator  into  the  condenser  coils. 

If  the  liquified  or  condensed  ammonia  collects 
promptly  in  the  liquid  receiver,  which  shows  on  the  gauge 
glass  of  same,  there  is  always  pressure  enough  behind  the 
expansion  valve  to  hold  the  ammonia  in  the  generator, 
and  there  will  be  no  danger  of  a  boil-over  unless  the  am- 
monia pump  receives  the  liquid  from  the  absorber  too 
fast.  To  avoid  this  the  absorber  is  always  supplied  with 


290  MECHANICAL  REFRIGERATION. 

a  gauge  glass,  so  the  ammonia  can  be  kept  at  a  certain 
height  by  means  of  a  valve  commonly  called  the  poor 
liquor  valve.  But  if  the  engineer  does  not  watch  it  very 
closely,  the  ammonia  will  get  out  of  his  sight,  and  some- 
times even  into  the  expansion  coils.  This  is  sometimes 
made  worse  by  not  having  a  governor  on  the  ammonia 
pump,  which  is  sure  to  vary  with  the  variation  in  steam 
pressure,  causing  the  pump  to  run  faster  or  slower. 

REMEDY  FOR  BOIL-OVER. 

If,  however,  through  carelessness  on  these  points  or 
otherwise,  a  boil-over  into  the  expansion  coils  has  taken 
place  it  may  become  necessary  to  nearly  close  the  expan- 
sion valve  long  enough  to  pump  a  vacuum  on  the  absorber, 
and  then  blow  what  gas  is  on  hand  through  the  coils. 
This  generally  cleans  them  and  takes  the  ammonia  back 
to  the  absorber.  This  is  rather  troublesome  work,  but 
the  work  will  have  to  be  done  before  the  machine  will 
work  satisfactorily. 

If  the  expansion  coils  are  divided  in  sections  sup- 
plied by  manifolds,  so  that  all  the  sections  except  one 
can  be  shut  off,  and  all  the  ammonia  gas  be  made  to  pass 
through  one  section  at  a  time,  each  of  the  sections  can 
be  cleaned  without  pumping  a  vacuum  on  the  absorber. 

CORRECTION  OF  AMMONIA  IN  SYSTEM. 

To  avoid  the  boil-over  or  siphoning  over,  the  gen- 
erator gauge  must  be  closely  watched,  as  has  already  been 
mentioned,  and  if  the  liquid  line  is  not  visible  in  the  gen- 
erator the  weak  liquor  should  be  cut  off  from  the  absorber, 
and  the  generator  glass  watched  to  see  if  the  liquid  rises; 
and  if  it  does,  and  no  part  of  thechargehas  goneioverinto 
condenser  or  brine  tank  coil,  and  the  absorber  has  been 
pumped  down  below  where  it  is  usually  carried,  it  is  a  plain 
case  of  shortage  of  aqua  ammonia.  If  there  is  no  frost 
on  the  pipes,  aud  the  receiver  glass  is  full  of  liquid,  the 
weak  liquor  valve  should  be  left  closed  and  the  expansion 
valve  opened  wider;  and  if  the  absorber  fills  without  much 
of  the  rumbling  noise,  it  is  filling  with  liquid  from  the 
brine  tank  coil.  If  the  machine  is  found  to  contain  enough 
ammonia,  and  there  is  no  leak  in  the  pans  or  the  equal- 
izer, and  the  head  pressure  is  too  low  and  the  back  press- 
ure too  high,  the  trouble  is  to  be  found  in  the  pump. 
But  if  the  high  pressure  is  too  low  and  the  low  pressure 
not  too  high,  with  everything  else  all  right,  the  machine 
should  have  an  addition  of  anhydrous  ammonia. 


MANAGEMENT  OF  ABSORPTION  PLANT.  291 

CLEANING  THE  ABSORBER. 

Most  cooling  waters  used  in  the  operation  of  absorb- 
ers in  connection  with  absorption  machines  contain 
carbonates  of  lime,  magnesia  and  iron  in  sufficient  quan- 
tity to  form  a  scale  inside  of  the  absorber.  This  scale 
consists  of  the  carbonate  of  lime,  etc.,  mentioned  before, 
which  becomes  insoluble  at  the  temperature  of  the  ab- 
sorber, owing  to  the  volatilization  of  the  free  carbonic 
acid  in  the  water  which  held  them  in  solution.  It  is  a 
matter  of  considerable  trouble,  but  also  of  necessity,  to 
remove  this  scale  from  time  to  time,  which  depends  on 
the  nature  of  the  water. 

This  is  generally  done  by  taking  the  coils  out  and 
suspending  them  over  a  fire  to  be  heated  considerably 
above  the  boiling  point  of  water  (not  red  hot,  however). 
While  still  hot,  or  better  still,  after  cooling,  the  scale 
may  be  removed  by  hammering  and  rolling  the  coil  about. 

As  a  much  simpler  device  Coddington  recommends 
the  use  of  crude  hydrochloric  acid  (price  two  and  a  half 
cents  per  pound)  diluted  with  six  times  its  weight  of 
water.  With  this  mixture  he  fills  up  the  coils  and  lets 
them  stand  until  it  ceases  to  digest  the  scale,  which 
usually  requires  two  hours.  If  one  dose  of  acid  does  not 
clean  the  pipe  thoroughly  he  repeats  the  same.  In 
this  case  it  is  not  required  to  remove  the  coils  at  all,  but 
only  the  bottom  and  top  of  the  absorber  have  to  be  dis- 
connected. Some  care,  however,  must  doubtless  be  ex- 
ercised, so  as  not  to  have  the  acid  act  for^too  long  a 
time,  as  in  that  case  the  iron  of  the  coil  itself  might  be 
affected. 

HIGH  PRESSURE  IN  ABSORBER. 

Too  high  pressure  in  the  absorber,  and,  incidentally 
thereto,  too  high  temperature  in  the  refrigerator,  may  be 
due  to  too  much  liquid  in  the  system,  or  to  too  little  cool- 
ing water.  Too  high  pressure  in  the  absorber  may  also 
be  due  to  air  or  permanent  gases  in  the  system.  These 
must  be  withdrawn  through  the  purge  cock  at  the  top  of 
the  absorber,  through  a  pipe  or  hose  leading  into  a  bucket 
of  water,  as  described  under  the  head  of  compression 
plant. 

OPERATING    THE  ABSORBER. 

It  is  often  claimed  that  the  absorber  runs  too  hot, 
which  may  be  due  to  the  presence  of  permanent  gases, 
due  to  decomposition  of  ammonia  or  to  the  presence  of 
air,  or  to  incrustation  of  the  pipes,  all  of  which  prevent 


292  MECHANICAL  REFRIGERATION. 

the  full  utilization  of  the  cooling  surface  of  the  con- 
denser. It  may  also  be  that  in  such  a  case  the  ex- 
changer does  not  do  its  full  duty  or  that  ammonia 
pump  is  not  in  good  working  order  and  that  it  does  not 
displace  a  sufficient  amount  of  liquid. 

Another  point  of  great  importance  in  this  respect  is 
the  proper  regulation  of  the  expansion  valve,  so  as  to 
prevent  any  excess  of  ammonia  entering  the  refrigerator 
and  the  absorber.  Any  ammonia  which  enters  the  ab- 
sorber in  a  non-volatilized  or  wet  condition,  means  so  much 
additional  heat  in  the  absorber,  more  cooling  water  and 
more  waste  all  around.  For  this  reason  we  are  advised 
to  so  regulate  our  expansion  valve  that  the  pressure  on 
absorber  gauge  is  about  three  pounds,  and  not  much  over. 

If,  on  the  other  hand,  there  is  too  little  or  no  press- 
ure on  the  absorber,  the  ammonia  pump  will  not  do  its 
duty,  and  this  will  be  prevented  by  the  foregoing  press- 
ure on  absorber  also.  In  order  to  correct  too  low  a  press- 
ure in  the  absorber  the  decrease  of  the  water  supply  to 
the  latter  is  generally  the  most  convenient  remedy. 

PACKING  AMMONIA  PUMP. 

The  packing  of  the  liquor  or  ammonia  pump  is  done 
the  same  way  as  in  case  of  any  other  pump,  but  owing  to 
the  pressure  and  the  smell  in  case  of  leaks  it  ought  to  be 
attended  to  with  special  precaution.  The  packing  used 
should  be  of  the  best  kind,  as  it  will  wear  least  on  the 
rods,  and  does  not  require  to  be  pulled  up  so  tight, 
which  increases  the  work  and  the  wear  and  tear.  The 
pump  rod  should  be  turned  true  if  unevenly  worn,  as  it 
is  next  to  impossible  to  pack  a  bad  rod  well. 

Any  good  hemp  packing  is  excellent  for  most  pumps. 
It  should  be  well  packed  into  the  stuffing  box,  but  not  too 
hard.  If,  after  screwing  down  the  nut  in  place,  the  box 
is  not  full,  remove  the  nut  again  and  put  in  more  pack- 
ing.  Replace  the  nut  and  screw  well  down,  not  too  tight. 
If  properly  done,  thumb  and  finger  will  screw  the  nut 
tight  enough.  The  piston  rod  should  be  kept  properly 
oiled.  The  packing  nuts  should  be.  tightened  up  from 
time  to  time,  and  the  packing  should  be  renewed  occasion- 
ally without  waiting  till  it  is  burned  out.  Some  operators 
use  pure  gum  rings  that  will  slip  into  the  stuffing  box  with 
light  pressure.  Square  or  rectangular  gums  will  answer 
if  the  rings  are  not  convenient  to  get.  This  packing 
must  not  be  screwed  down  too  tight,  as  the  ammonia 


MANAGEMENT  OF  ABSORPTION  PLANT.  293 

will  swell  the  rubber,  and  in  that  case  it  may  bind  the  rod 
so  tightly  that  it  will  roll  it  out  of  the  stuffing  box.  Use 
mineral  oil  for  lubricating. 

ECONOMIZING  WATER. 

The  economizing  of  water  is  a  question  of  even  more 
importance  with  the  absorption  system  than  with  the 
compression  system,  as  it  is  used  not  only  in  the  condenser 
and  boiler,  but  also  for  the  absorber.  In  this  case  also 
it  can  be  recooled  and  re-used  by  gradation,  and  in  locali- 
ties where  the  water  is  warm,  it  may  be  good  policy  to 
cool  it  by  gradation  in  the  first  place.  The  water  after  hav- 
ing passed  the  absorber  is  better  for  boiler  feeding  than 
the  natural  water,  not  only  because  it  is  heated  to  some 
extent  already,  but  also  because  it  has  already  deposited 
some  or  most  of  its  mineral  matter  which  would  tend 
to  form  scale  in  the  boiler.  The  cooling  water  after  hav- 
ing left  the  absorber  might  be  used  to  condense  the 
moist  steam  from  ammonia  pump,  in  case  this  is  also 
needed  for  ice  making  before  it  enters  the  boiler.  Some 
absorption  machines  use  the  cooling  water  for  the 
double  purpose  of  cooling  the  absorber  first,  and  then 
the  condenser,  or  vice  versa. 

OPERATING  BRINE  TANK. 

The  principal  information  relating  to  brine  and 
freezing  tanks  is  given  elsewhere.  The  following  may  be 
added  relative  to  their  operation:  In  order  to  be  able  to 
fully  utilize  the  coils  in  brine  tanks,  they  should  be 
made  in  short  runs,  and  kept  free  from  ice.  Sometimes 
when  the  brine  is  not  strong  enough,  the  formation  of 
ice  around  the  expansion  coil  may  take  place,  and 
this  greatly  reduces  the  capacity  of  the  freezing  tank, 
and  in  some  measure  accounts  for  the  great  variation  in 
pipe  lengths  required  in  different  plants.  No  galvanized 
iron  pipe  should  be  used  for  direct  expansion,  and  con- 
nections, etc.,  should  be  made  with  extra  strong  unions, 
flanged  joints,  etc.  No  right  and  left  coupling,  nor  ordi- 
nary couplings  should  be  used,  and  the  element  of  un- 
certainty should  be  entirely  avoided. 

LEAKS  IN  BRINE  TANKS. 

Small  leaks  in  brine  tanks  may  sometimes  be  stopped 
by  the  application  of  bran  or  corn  meal  near  the  place 
where  the  leak  is.  The  meal  or  bran  should  be  carried 
(in  small  portions  at  the  time)  to  the  place  where  the  leak 
is,  by  means  of  a  short  piece  of  open  pipe. 


294  MECHANICAL  REFRIGERATION. 

In  making  repairs  to  coils  while  immersed  in  brine 
the  workmen  should  besmear  their  arms  and  hands  with 
cylinder  oil,  lard  or  tallow,  as  that  will  enable  them  to 
keep  them  in  the  cold  brine  without  much  inconven- 
ience for  some  time. 

TOP  AND  BOTTOM  FEED  BRINE  COILS. 

The  expansion  coils  in  brine  tanks  are  fed  from  bot- 
tom or  top  according  to  the  system  of  refrigeration,  as 
mentioned  elsewhere,  but  it  is  claimed  that  the  disad- 
vantages of  both  ways  of  feeding  can  be  avoided  by 
using  what  is  called 

TOP  FEED  AND  BOTTOM  EXPANSION. 

This  system  is  a  combination  of  the  best  elements 
of  the  two  systems  above  described.  Each  alternate 
coil  in  a  tank  is  connected  to  a  liquid  manifold  (provided 
with  regulating  valves)  at  the  top  of  the  tank,  and  the 
ammonia  is  evaporated  downward  through  one-half  of 
the  coils  in  the  tank.  All  of  the  coils  in  the  tank  are 
connected  to  a  large  bottom  manifold  (which  might  be 
called  an  equalizing  expansion  manifold),  and  the  gas  is 
returned  up  through  the  second  half  of  the  coils  to  a 
gas  suction  manifold  at  the  top  of  the  tank,  located  be- 
hind and  a  little  above  the  liquid  manifold.  The  suction 
manifold  is  provided  with  a  tee  for  connecting  the 
suction  pipe  leading  to  the  compressors. 

CLEANING  BRINK  COILS. 

When  the  pipes  in  the  brine  tank  are  to  be  blown 
out  by  steam,  the  brine  must  be  removed  and  the  head- 
ers of  the  coils  must  be  disconnected  and  each  coil  must 
be  steamed  out  separately  with  dry  steam,  care  being 
taken  to  let  the  steam  blow  through  the  coils  long 
enough  to  heat  them  thoroughly,  so  that  when  the  steam 
is  shut  off  the  coils  are  left  hot  enough  to  absorb  all 
moisture  inside. 

DRIPPING  CEILING. 

Dripping  ceiling  is  an  awkward  trouble  liable  to  oc- 
cur where  rooms  are  to  be  refrigerated.  There  seems  to 
be  no  universal  cure  for  a  dripping  ceiling;  even  as  to 
the  causes  of  such  occurrence  the  most  experienced  en- 
gineers seem  to  have  only  conjectures.  In  some  cases  it 
seems  that  in  storage  rooms  located  one  above  the  other 
the  ceiling  of  the  lower  drips  on  account  of  the  cold 
iloor  above.  In  other  cases  it  appears  that  the  space 
between  the  ceiling  and  refrigerating  coils  is  too  small, 


MANAGEMENT  OF  ABSORPTION  PLANT.  205 

allowing  condensation  to  form  on  the  ceiling  which  oth- 
erwise would  have  settled  on  the  pipes  again.  It  is 
asserted  that  porous  ceilings,  formed  with  brick  arches 
laid  in  ordinary  mortar,  will  prevent  condensation  over- 
head, while  ceilings  formed  of  sheet  metal,  wood 
painted,  and  varnish  air  tight  and  ditto  cement  ceilings 
are  prone  to  condense  moisture.  The  dripping  from  re- 
frigerating coils  should  be  caught  in  drip  pans  placed  or 
hung  below  them,  and,  generally  speaking,  the  drippings 
ought  to  be  prevented  from  entering  the  fermenting 
tubs,  dripping  over  meat,  vegetables  and  cold  storage 
goods  in  general. 

REMOVING  ICE  FROM  COILS. 

The  removal  of  ice  from  ammonia  expansion  coils 
can  be  best  effected  by  allowing  hot  ammonia  vapor  to 
enter  them,  and  a  connection  to  permit  this  should  be 
provided  for.  The  ice  can  be  thawed  off  in  this  way  or 
loosened  so  that  it  can  be  knocked  off.  If  the  ice  is  re- 
moved soon  after  it  has  formed,  say  daily,  it  is  sufficiently 
loose  in  itself,  so  that  it  can  be  cleaned  off  without  any 
special  artifices. 

MANAGEMENT  OF  OTHER  PLANTS. 

The  management  of  other  refrigeration  plants,  notably 
of  those  which  work  on  the  compression  plan,  such  as  the 
sulphurous  acid,  the  carbonic  acid  and"  Pictet liquid " 
machines,  is  in  most  principal  points  like  that  of  the 
ammonia  compression  machines.  In  the  case  of  carbonic 
acid  it  is  somewhat  difficult  to  detect  and  locate  leaks 
on  account  of  its  being  free  from  odor.  The  best  avail- 
able means  in  this  connection  are  soapsuds,  smeared 
over  the  pipes,  joints,  etc.,  when  leaks  will  demonstrate 
themselves  by  the  formation  of  bubbles. 

COST  OF  REFRIGERATION. 

The  principal  expense  in  the  production  of  artificial 
refrigeration  and  artificial  ice  IB  coal  and  labor.  And  as 
it  takes  much  less  labor  in  proportion  to  run  a  large 
plant  than  a  small  one,  it  is  evident  that  larger  plants, 
especially  for  ice  making,  are  more  profitable.  Also  less 
coal  is  required  for  larger  than  for  smaller  plants.  While 
four  men  are  required  to  operate  ice  plants  of  one  to  five 
tons  capacity,  it  will  take  only  five  men  to  operate  a  10- 
ton  plant,  and  only  eight  men  to  operate  a  35-ton  plant, 


206  MECHANICAL  REFRIGERATION. 

CHAPTER  XVI.— TESTING  OF  PLANT. 

TESTING   OF  PLANT. 

The  testing  of  a  plant  is  executed  in  different  ways 
in  accordance  with  what  the  test  is  intended  to  prove. 
When  the  question  is  simply  as  to  what  a  plant  can  be 
made  to  do,  independent  of  the  use  of  coal,  the  use  of 
condensing  water  and  the  wear  and  tear  of  machinery, 
the  test  is  simply  a  matter  of  shoveling  coal  and,  pumping 
condenser  water.  However,  the  time  of  such  tests  has 
gone  by,  and  the  question  nowadays  is,  as  to  what  a  ma- 
chine will  do  under  normal  comparable  conditions  and  as 
to  how  the  refrigeration  produced  compares  with  the 
amount  of  work  expended  and  the  amount  of  coal  con- 
sumed. 

FITTING  UP  FOR  TEST. 

To  make  a  test  of  this  kind  a  number  of  preparations 
have  to  be  made.  The  compressor  as  well  as  the  steam  en- 
gine has  to  be  provided  with  indicators;  the  condensing 
water  supply  has  to  be  connected  with  a  meter,  and  the 
amount  of  brine  circulated  must  be  ascertained  in  a 
similar  manner.  The  temperature  of  incoming  and  out- 
going brine,  of  the  incoming  and  outgoing  condenser 
water,  must  be  measured  as  exactly  as  possible,  as  also 
the  actual  temperature  of  the  gas  when  entering  and 
leaving  the  compressor,  for  which  purpose  mercury 
wells  should  be  placed  in  the  suction  and  discharge  pipe 
near  the  compressor.  , 

MERCURY  WELLS. 

A  mercury  well  is  simply  a  short  piece  of  pipe,  closed 
at  one  end  and  fitted  tightly  into  a  pipe  or  vessel,  the 
temperature  of  which  is  to  be  ascertained.  The  pipe  is 
filled  with  mercury,  and  an  exact  thermometer  is  placed 
in  the  latter. 

THE  INDICATOR  DIAGRAM. 

An  indicator  diagram  shows  the  outline  of  a  surface, 
limited  on  one  side  by  a  horizontal  line,  the  length  of 
which  represents  the  length  of  the  stroke  of  a  piston  (of  a 
pump,  engine,  compressor,  etc.),  in  reduced  scale.  A  line 
connecting  the  two  ends  of  the  straight  line  overhead  is 
formed  by  connecting  the  points,  which  by  their  vertical 
distance  from  the  said  horizontal  line  indicate  the  press- 
ure working  on  the  piston  when  passing  their  respective 
points  on  the  horizontal  line  on  a  certain  scale. 


TESTING  OF  PLANT.  207 

These  diagrams  are  obtained  by  instruments  called 
indicators,  which  are  applied  in  accordance  with  instruc- 
tions accompanying  each  instrument  when  bought. 

The  area  of  such  a  diagram  limited  by  a  straight 
line  on  one  side  and  by  a  curve  on  the  other  sides,  repre- 
sents the  work  done  by  the  compressor  during  one  stroke 
in  foot-pounds. 

The  area  of  the  diagram  may  be  found  by  calculation 
in  dividing  the  same  into  convenient  sections,  measuring 
them  and  adding  them  up. 

The  area  may  also  be  measured  by  a  machine  con- 
structed for  this  purpose,  called  a  planimeter. 

With  proper  precaution  and  an  accurate  scale,  the 
area  of  these  diagrams  can  also  be  ascertained  by  cutting 
them  out  carefully  and  weighing  them.  The  weight  so 
obtained  can  then  be  compared  with  that  of  a  rectangu- 
lar piece  of  paper  of  the  same  thickness  and  known  sur- 
face. 

In  addition  to  the  actual  work  done  by  or  applied 
to  a  piston  during  each  stroke,  these  diagrams  show  at 
a  glance  the  conditions  of  pressure  at  the  different  posi- 
tions of  the  piston,  give  also  a  ready  idea  of  the  regular- 
ity of  its  working,  the  working  of  the  valves  and  the 
changes  of  temperature. 

CALCULATION  OF  DIAGRAM. 

Usually,  and  in  the  absence  of  a  planimeter,  the  indi- 
cator diagram  of  the  compressor  is  divided  into  ten  ver- 
tical stripes,  the  median  heights  of  which  are  added  and 
divided  by  10.  whereby  the  median  height  of  the  dia- 
gram is  found  in  inches  or  millimeters.  As  it  is  known 
for  every  indicator  spring  what  pressure  corresponds  to 
one  millimeter  or  to  one  inch  or  fraction  of  an  inch,  we 
can  readily  find  the  mean  pressure  of  the  compressor  from 
the  average  height  of  the  diagram.  The  average  pressure 
in  pounds  per  square  inch  multiplied  by  the  area  of  the 
piston  in  square  inches  and  by  the  number  of  feet  trav- 
eled by  the  same  per  minute  gives  the  work  of  the  com- 
pressor in  foot-pounds  per  minute,  which  may  be  divided 
by  33,000  to  find  the  horse  power  of  the  compressor.  In 
close  calculations  allowance  must  be  made  for  the  thick- 
ness of  the  piston  rod  in  double-acting  compressors,  as 
the  area  of  the  piston  is  lessened  on  one  side  to  that  ex- 
tent. It  is  also  well  to  obtain  a  number  of  indicator  dia- 
grams at  intervals  of  from  ten  to  thirty  minutes. 


MECHANICAL  REFRIGERATION. 


MEAN  PRESSURE  OF  COMPRESSOR. 

In  the  absence  of  an  indicator  diagram  the  mean 
pressure  in  the  compressor,  and  indirectly  the  work  of 
the  compressor,  may  be  found  approximately  in  the 
accompanying  table  (De  La  Vergne's  catalogue)  from 
the  refrigerator  and  condenser  pressure  and  temperature. 


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TESTING  OF  *» LANT. 


->-    A 


INTERPRETATION  OF  DIAGRAM. 

In  order  to  interpret  the  compressor  diagram  with 
regard  to  the  working  of  the  compressor,  its  valves, 
defects,  etc.,  Lorenz  gives  the  following  outlines: 

If  all  parts  of  the  machine  are  in  proper  condition, 
the  general  appearance  of  the  diagram  will  be  that  repre- 
sented in  Fig.  1.  The  suction  line,  <S,  is  only  a  little  be- 
low the  suction  pressure  line,  v  v,  and  the  pressure  line, 
d,  is  only  a  little  higher  than  the  condenser  pressure,  k  fc, 
Fig.  1.  The  work  required  to  open  the  compressor  valves 
is  indicated  by  small  projections  at  the  pressure  and  suc- 
tion line,  and  the  influence  of  clearance  is  shown  by  the 
curve  r.  This  curve  cuts  the  back  pressure  line  after  the 
piston  has  commenced  to  trav- 
el back,  and  therefore  lessens 
the  suction  volume  to  that  ex- 
tent. The  diagram  also  shows 
that  the  vapors  are  taken  in  by 
the  compressor,  not  at  the  back 
"pressure,  but«at  what  maybe 
termed  the  suction  pressure, 
which  is  somewhat  lower.  For 
this  reason  it  is  that  the  com- 
pression curve,  c,  does  not  intersect  the  back  pressure 
line  until  after  the  piston  has  changed  the  direction  of 
its  movement.  The  theoretical  volume  of  the  compres- 
sor, as  indicated  by  the  line  v  v,  is  therefore  lessened  in 
practical  working  for  vapors  possessing  a  certain  tension. 

EXCESSIVE    CLEARANCE. 

The  diagram  of  a  compressor  having  an  excessive 
amount  of  clearance  is  shown  in  Fig.  2.  It  is  character- 


afm 


FIG.  1. 


FIG.  2.  FIG.  3. 

ized  by  a  flat  course  of  the  back  expansion  line  r,  Fig.  2, 
thus  lessening  the  useful  volume  of  the  compressor. 
In  a  similar  manner  the  binding  of  the  pressure  valve 


300 


MECHANICAL  REFRIGERATION. 


is  shown  by  the  diagram,  Fig.  3,  which  may  be  caused  by 
an  inclined  position  of  the  guide  rod  of  the  valve.  This 
same  deficiency  causes  also  frequently  a  delay  in  the  open- 
ing of  the  pressure  valves,  which  is  indicated  by  a  too 
great  projection  in  the  pressure  line,  as  is  also  shown  in 
Fig.  3.  After  the  valve  is  once  opened  the  pressure  line 
pursues  its  normal  course  until  the  piston  starts  back- 
ward, when  the  defect  is  again  shown  in  the  back  press- 
ure line,  as  stated. 

IRREGULAR  PRESSURE  AND  STIFF    VALVE. 

Much  work  is  also  lost  when  the  resistance  in  the 
pressure  and  suction  pipes  is  too  great,  respectively,  when 
the  valves  are  weighted  too  much.  In  such  cases  the  dia- 
gram has  the  appearance  shown  in  Fig.  4,  in  which  the 


FIG.  4. 


FIG.  5. 


pressure  and  suction  line  are  at  a  comparatively  great 
distance  from  the  condenser  pressure  line  and  the  back 
pressure  line.  If  this  happens  the  valve  springs  should 
be  replaced  by  weaker  ones;  and  if  this  does  not  have  a 
noticeable  effect,  the  pipe  lines  and  shutting  off  valves 
must  be  thoroughly  inspected  and  cleaned  if  necessary. 

The  binding  of  the  suction  valve  causes  a  consider- 
able decline  in  the  pressure  at  the  commencement  of  the 
suction,  and  is  therefore  shown  by  an  increased  projec- 
tion in  the  beginning  of  the  suction  line,  as  shown  in 
Fig.  5.  At  the  commencemeut  of  compression  this  de- 
fect shows  itself  by  a  delay  in  the  compression,  which  is 
also  indicated  in  the  diagram,  Fig.  5. 

LEAKY  VALVE  AND  PISTON  PACKING. 

Leaking  of  the  compressor  valves  is  shown  in  the  dia- 
gram illustrated  in  Fig.  6.  The  projections  in  the  com- 
pression and  suction  line  do  not  appear,  but  the  compres- 
sion line  passes  gradually  into  the  pressure  line,  and  the 
back  expansion  line  passes  gradually  into  the  suction  line. 
If  the  leak  in  the  pressure  valve  predominates  the  com- 


TESTING  OF  PLANT.  301 

pression  curve  is  almost  a  straight  line,  and  steep;  and  if 
the  leak  in  the  suction  valve  predominates  the  compres- 
sion line  runs  in  a  father  flat  course. 

If  the  piston  is  not  well  packed,  and  leaks,  the  vapors 
are  allowed  to  pass  from  one  side  of  the  piston  to  the 


FIG.  6.  FIG.  7. 

other,  thus  causing  a  very  gradual  compression,  and  a 
consequent  flat  course  of  the  compression  line,  as  shown 
in  Fig.  7.  On  the  other  hand,  it  will  take  a  longer  time 
before  the  suction  line  reaches  its  normal  level  on  the 
backward  stroke,  as  the  suction  valve  is  prevented  from 
opening  until  the  velocity  of  the  piston  is  so  great  that 
the  vapors  passing  the  piston  are  no  longer  sufficient  in 
amount  to  fill  the  suction  space.  Then  the  pressure  de- 
creases gradually,  and  the  suction  valve  begins  to  play, 
which  is  also  signified  in  the  diagram,  Fig.  7.  Several  of 
the  defects  mentioned  may  exist  at  the  same  time. 

MAXIMUM  AND  ACTUAL  CAPACITY. 

The  maximum  theoretical  capacity  of  a  machine  is 
the  measure  of  what  the  same  could  possibly  do  under  the 
existing  conditions.  (Temperature  of  brine,  amount  and 
temperature  of  cooling  water.) 

The  actual  capacity  is  expressed  by  the  amount  of 
refrigeration  actually  produced.  It  is  all  the  way  from  15 
to  30  per  cent  less  than  the  maximum  theoretical  capac- 
ity. This  is  a  natural  consequence  of  the  impossibility 
of  avoiding  leakage,  clearance,  friction,  transmission  of 
heat  to  the  refrigerating  medium  on  its  passage  to, 
through,  and  from  the  compressor,  etc. 

COMMERCIAL  CAPACITY. 

Frequently  the  term  commercial  capacity  is  used, 
and  is  meant  to  indicate  what  a  machine  would  do  under 
what  may  be  called  average  conditions  as  regards  back 
pressure,  condenser  pressure,  etc.  It  is  readily  under- 
stood, however,  that  as  long  as  such  average  backpress- 
ure and  condenser  pressure  is  not  generally  agreed  upon, 


302 


MECHANICAL  REFRIGERATION. 


the  term  commercial  capacity  is  indefinite.  A  back 
pressure  of  about  twenty-five  pounds  and  a  condenser 
pressure  of  about  140  pounds  have  been  proposed  by 
Richmond  as  such  average  conditions. 

NOMINAL  COMPRESSOR  CAPACITIES. 

The  following  table  shows  the  approximate  dimen- 
sions of  a  few  compressors,  together  with  what  may  be 
termed  their  nominal  or  commercial  capacity.  The 
theoretical  capacity  for  various  back  pressures,  etc.,  may 
be  found  by  referring  to  the  subjoined  table,  which  gives 
the  capacity  in  tons  in  24  hours,  for  various  compressor 
capacities  per  minute: 

TABLE  SHOWING  NOMINAL  COMPRESSOR  CAPACITIES. 


Number  of  compressor  

1 

2 

3 

4 

5 

Diameter  of  compressor  in  inches  (2r) 
Length  of  stroke  in  inches  (b)  

5 

8 

6K 
12 

9 
16 

10 

20 

18 

28 

Volume  of  compressor  in  cubic  feet 

rz  bx3.14 

0  09 

0  23 

0  58 

0  89 

4  12 

1728          

Number  of  revolutions  per  minute(wi) 

90 

90 

70 

68 

60 

Capacity  of  compressor  (single  act- 
ing) per  minute  in  cubic  feet  (Vm) 
Nominal  or  commercial  capacity  in 

8.1 

20.7 

41 

60.5 

247 

tons  of  refrigeration  in  twenty- 

four  hours  about  ..    .       .... 

2 

5 

10 

15 

60 

ACTUAL  REFRIGERATING  CAPACITY. 

In  case  of  brine  circulation  the  actual  refrigerating 
capacity,  J2,  in  twenty-four  hours  is  found  after  the 
formula— 

p_PXsX(*— tt] 
284,000 


tons. 


in  which  P  is  the  number  of  pounds  of  brine  circulated 
in  twenty-four  hours,  and  t  the  temperature  of  the  re- 
turning, and  *i  the  temperature  of  the  outgoing  brine; 
s  is  the  specific  heat  of  the  brine. 

FRICTION  OF  COMPRESSOR. 

The  amount  of  friction  or  lost  work  of  compressor 
is  equal  to  the  difference  of  the  work  shown  by  the  indi- 
cator diagram  of  the  engine  and  that  of  the  compressor. 
The  total  work  used  by  the  compressor  is  equal  to  that 
shown  by  the  engine  indicator  diagram. 


TESTING  OF  PLANT.  303 

HEAT  REMOVED  BY  CONDENSER. 

The  total  heat,  H,  removed  by  the  condenser  is  found 
by  the  formula— 

H    Px(t  —  tJ  units, 

in  which  P  is  the  amount  of  condenser  water  circulated 
in  a  certain  time  (twenty-four  hours),  and  t  and  tlt  the 
temperatures  of  the  outgoing  and  incoming  condenser 
water,  respectively. 

MAXIMUM  THEORETICAL  CAPACITY. 

The  maximum  theoretical  refrigerating  capacity,  Bvi 
of  the  compressor  is  found  after  the  formula  — 


1  200  v  ' 

in  which  formula  C  stands  for  the  compressor  volume 
per  minute,  i.  e.,  for  the  space  through  which  the  com- 
pressor piston  travels  per  minute;  v  is  the  volume  of  one 
pound  of  vapor  at  the  temperature  tt,  in  cubic  feet;  t  is  the 
temperature  in  the-  condenser,  and  tt  the  temperature  of 
the  ammonia  in  suction  pipe;  h  is  the  latent  heat  of 
volatilization  of  one  pound  of  ammonia  at  the  tempera- 
ture of  tt. 

The  compressor  volume  per  minute,  C,  is  found  after 
the  formula— 

G  d*  X  ZX  wXO.785, 

in  which  m  is  the  number  of  revolutions  (single-acting), 
d  the  diameter,  and  I  the  length  of  stroke  in  feet. 

If  a  compressor  works  with  wet  gas  the  volume,  v, 
may  be  taken  from  the  table  for  saturated  ammonia  on 
page  94;  if  it  works  with  dry  gas  the  volume,  v,  should  be 
taken  from  the  table  on  superheated  ammonia  vapor  on 
page  311.  In  the  latter  case  both  the  pressure  and 
temperature  of  ammonia  in  suction  pipe  should  be 
ascertained. 

At  the  temperatures  and  pressures  not  filled  out 
in  table  the  ammonia  exists  as  a  liquid.  Other  approx- 
imate values  may  be  found  after  the  formula-— 

280  rf  0.821; 

v  =  —  -  (see  page  96). 

CORRECT  BASIS  FOR  CALCULATION. 

The  foregoing  method  for  the  calculation  of  maximum 
theoretical  capacity  is  based  on  the  temperatures  of  the 
ammonia  vapor  in  suction  pipe*and  in  the  condenser.  It  is, 


304 


MECHANICAL  REFRIGERATION. 


however,  argued  (by  Linde  and  others) — and  with  consid- 
erable force,  we  think— that  the  temperatures  of  brine 
leaving  the  brine  tank,  and  of  water  leaving  the  conden- 
ser should  be  used  instead.  The  latter  method  is  fol- 
lowed in  the  calculation  relating  to  the  compression  ma- 
chine on  page  115,  etc.  It  is  true  the  results  obtained 
by  the  former  method  of  calculation  will  come  nearer  to 
the  practical  results,  but  those  obtained  by  the  latter 
method  will  give  more  comparable  results  as  regards  the 
efficiency  of  different  machines. 

MORE  ELABORATE  TEST. 

For  more  elaborate  tests,  the  loss  of  refrigeration  in 
engine  rooms  and  a  number  of  other  details  must  be  con- 
sidered, and  additional  mercury  wells  will  be  necessary. 

TABLE  SHOWING  DATA  OF  TEST. 

The  following  table  showing  another  series  of  tests 
made  by  Schroeter,  at  Munich,  gives  the  different  quan- 
tities which  should  be  ascertained,  and  they  also  show 
the  difference  in  efficiency  of  one  and  the  same  machine 
if  worked  under  different  conditions: 


NUMBER  OF  EXPERIMENT. 

1 

2 

8 

STEAM  ENGINE. 

48  3 

49 

64 

Temperature  of  feed  water,  °  F  .  .  .  . 

71 

70 

84 

Mean  pressure  (Indicator),  pounds  per 
square  inch.  

26  2 

26  3 

33  5 

Revolutions  per  minute 

44  91 

45  10 

44  07 

18  88 

18  99 

24  06 

COMPRESSOR. 

Work  done  by   compressor  in  horse 
powers          .        ....            

15  31 

14  98 

21  54 

P  ressure  in  condenser  coils  
Pressure  in  refrigerator  coils  .... 

135.2 
55  2 

131.2 
41  89 

199.2 
41  9 

REFRIGERATOR. 

Temperature  of  incoming  brine  
Temperature  of  outgoing  brine        .. 

42.8 
37  2 

28.37 
22  97 

28.35 
22  99 

Brine  circulating  per  hour  in  Ibs.  .. 

65051 

50364 

43  115 

Specific  gravity  of  brine                . 

1  250 

1  250 

1  947 

850 

.846 

845 

Heat  absorbed  in  refrigerator  in  cal- 

310,335 

230,657 

195920 

CONDENSER. 

Temperature  of  condenser  water  °  F.  . 
Temperature  of    outgoing   condenser 
water                      ... 

49.21 
67  57 

49.17 
67  34 

40.42 
95  60 

Amount  of  condenser  water  per  hour, 
pounds                 ..        

nl9338 

15041 

5,328 

Heat  absorbed  in  condenser  in  calories 
Horse  power  produced  by  engine  per 
1  000  units  refrigeration 

356,950 
060 

273,891 
082 

248,680 
123 

Horse  power  used  in  compressor  per 
1  000  units  refrigeration  

049 

065 

.109 

Pounds  of  condensing  water  used  per 

63 

65 

27 

TESTING  OF  PLANT.  305 

EFFICIENCY  OF  ENGINE  AND  BOILER. 

To  determine  the  efficiency  of  engine  and  boiler  the 
amount  of  coal  used  per  indicated  horse  power  of  engine 
must  also  be  ascertained.  Frequently  also  the  amount 
of  steam  used  by  the  engine  is  determined  by  means  of 
calorimetric  test.  (See  page  109.) 

TEST  OF  ABSORPTION  PLANT. 

The  testing  of  an  absorption  plant  can  be  executed 
on  similar  lines,  and  the  various  movements  of  efficiency 
can  be  calculated  from  the  elements  of  the  test,  refer- 
ence being  had  to  the  formulas  given  in  the  chapter  on 
the  absorption  machine.  For  crude  tests  the  amount  of 
coal  used  within  a  certain  time,  to  heat  the  ammonia 
still  and  to  propel  the  ammonia  pump,  is  directly  com- 
pared with  the  amount  of  ice  produced  or  with  the  re- 
frigeration, as  it  can  be  measured  by  the  work  done  in 
brine  tank  as  shown  in  the  foregoing. 

MORE  EXACT    TESTS. 

For  more  exact  tests,  the  temperature  and  pressure 
in  the  different  parts  of  the  plant  must  be  closely  ob- 
served, the  work  done  by  the  ammonia  pump  must  be 
ascertained,  the  strength  of  weak  and  rich  liquor  and  a 
number  of  other  items  must  be  recorded  in  order  to  ob- 
tain not  only  an  idea  of  the  actual  capacity  of  the  plant, 
but  also  to  learn  in  what,  if  in  any,  respect  the  same  is 
falling  short,  and  in  what  direction  a  possible  remedy 
may  be  looked  for.  To  show  more  clearly  what  is  wanted 
in  this  direction,  we  append  the  tabulated  record  of  a 
test  made  of  an  absorption  machine  by  Prof essor  Denton 
some  time;  not  that  we  think  it  represents  an  exemplary 
capacity,  but  simply  to  show  how  the  items  of  the  test 
may  be  arranged. 

DISCUSSION  OF  TABLE. 

The  actual  amount  of  coal  used  is  not  measured  in 
the  foregoing  test.  If  we  assume  that  one  pound  of 
coal  makes  about  eight  pounds  of  steam,  the  foregoing 
test  shows  that  one  pound  of  coal  would  give  a  refriger- 
ating effect  equivalent  to  the  melting  of  somewhat  less 
than  fourteen  pounds  of  ice,  which  would  correspond  to  an 
actual  ice  making  capacity  of  about  seven  pounds  of  ice 
per  pound  of  coal.  From  a  letter  written  from  southern 
Louisiana,  recently  shown  us,  it  appears  that  an  absorp- 
tion machine  in  regular  operation  in  that  locality  fur- 


306 


MECHANICAL  REFRIGERATION. 


nishes  eight  pounds  of  ice  per  pound  of  coal  used  as  a 
minimum. 

TABLE  SHOVING  RESULTS  OF  TEST. 

Average  pressures  above  atmosphere,  generator  Ibs.  per  sq.  in.  160.77 

steam  "      47.70 

cooler  23.69 

absorber  "      23.4 

temperatures,  deg.  F.,  generator 272. 

condenser  inlet 64H . 

outlet 80. 

range 25H . 

,    brineinlet 21.20 

outlet 16.14 

range 5.06 

absorber  inlet 80. 

outlet 111. 

range 31. 

heater  upper  outlet  to  generator  212. 
lower  "      absorber  178. 

inlet  from  132. 

inlet  from  generator 272. 

water  returned  to  main  boilers  .    260. 

Steam  per  hour  for  boiler  and  ammonia  pumps,  Ibs 1,986. 

Brine  circulated  per  hour,  cu.  ft 1,633.7 

pounds 119,260 

"     specific  heat  0.800 

1     heat  eliminated  per  lb.,  B.  T.  U 4.104 

"     cooling  capacity  per  24  hours,  tons  of  melting  ice..  .     40.67 

"   lb.  of  steam,  B.  T.  U 243. 

"     ice  melting  capacity  per  10  Ibs.  of  steam,  Ibs 17.1 

Heat  rejected  at  condenser  per  hour,  B.  T.  U 918,000 

"absorber          "  "       1,116,000 

"    consumed  by  gen.  per  lb.  of  steam  condensed,  B.  T,  U.          932 

Condensing  water  per  hour,  Ibs 36,000 

coil,  approx.  sq.  ft.  of  surface 870 

Absorber        "  "       "        " 350 

Steam  "       "        "       200 

Pump  ammonia,  dia.  steam  cyl.,  in 9 

'     ammonia  cyl.,  in 3% 

'    stroke,  in 10 

'    revolutions  per  minute 22 

brine  steam  cyl.,  diam.,  in 914 

"     brine      ' 8 

stroke,  in 10 

revolutions  per  min 70 

Effective  stroke  of  pumps  0.8  of  full  stroke. 

ESTIMATES    AND    PROPOSALS. 

By  way  of  recapitulation  it  may  be  mentioned  that  in 
ordering  refrigerating  machines,  or  in  asking  for  esti- 
mates or  proposals,  one  cannot  be  too  explicit  in  stating 
the  conditions  under  which  the  plant  is  calculated  to 
work  and  what  it  is  expected  to  accomplish.  Foremost 
should  be  stated: 

First.—  The  temperature  and  quantity  of  the  available 
water  supply  should  be  given  under  all  circumstances, 
and  also  the  average  temperature  during  the  different 
seasons,  if  possible. 

Second.— If  water  power  or  a  surplus  of  steam  power 
is  available,  it  should  be  specified;  also  the  price  and 
kind  of  coal,  if  possible, 


TESTING  OF  PLANT.  307 

Third.—  The  kind  of  machine  that  is  required, 
whether  absorption  or  compression,  and  whether  am- 
monia or  some  other  refrigerating  agent  is  to  be  used. 

In  case  the  principal  object  of  the  plant  is  the  pro- 
duction of  ice,  the  following  additional  points  should  be 
clearly  specified: 

(a)  If  absolutely  pure  and  clear  ice  is  required,  i.  e.t 
ice  made  from  distilled  water,  or  whether  opaque  and 
relatively  impure  ice  will  answer. 

(6)  If  the  required  buildings  are  to  be  erected  in 
wood  or  masonry,  or  if  already  existing  buildings  are  to 
be  utilized,  and  in  the  latter  case,  dimensions  and  mode  of 
construction. 

(c)  The  amount  of  ice  that  is  to  be  produced  in 
twenty-four  hours. 

MISCELLANEOUS  REFRIGERATION. 

For  the  refrigeration  of  rooms  in  breweries,  packing 
houses  or  cold  storage  establishments,  etc.,  the  follow- 
ing additional  points  should  be  specified,  or  as  many  of 
them  as  is  practicable. 

(a)  If  the  rooms  are  to  be  refrigerated  by  direct  ex- 
pansion or  by  brine  circulation. 

(6)  The  size  of  rooms,  the  construction  of  the  walls 
and  the  temperature  at  which  they  are  to  be  held. 

(c)  The  amount  and  kind  of  beer  to  be  brewed,  and 
the  time  it  is  proposed  to  be  kept  in  storage  in  case  of  a 
brewery. 

(d)  In  the  case  of  a  packing  house,  the  number  and 
kind  of  animals  to  be  chilled  daily,  and  the  number  and 
kind  of  carcasses  to  be  frozen,  and  the  length  of  time 
they  are  to  be  kept  in  storage. 

(e)  In  the  case  of  a  cold  storage  establishment,  the 
nature  of  the  products  to  be  stored,  or  the  temperature 
at  which  they  are  to  be  held,  and  the  amount  of  what  is 
to  be  placed  into  cold  storage  daily. 

CONTRACTS. 

In  case  contracts  are  made  for  refrigerating  machin- 
ery, the  amount  of  coal  and  water  to  be  used  for  a  cer- 
tain specified  duty,  should  apply  to  a  specified  kind  of 
coal,  to  the  temperature  of  the  actual  water  supply  (not 
to  fictitious  conditions),  and  to  a  specified  number  of  rev- 
olutions of  compressor  or  pump  for  specified  dimensions. 


& 

If-** 


[DIE 


,wV     OF  THE          'AA 

\\    UNIVERSITY    ) 


308  MECHANICAL  REFRIGERATION. 

In  order  to  ascertain  the  amount  of  refrigeration 
which  may  be  expected  from  an  existing  compressor, 
the  diameter,  length  of  stroke  and  number  of  revolutions 
should  be  given.  Also  state  whether  single  or  double- 
acting;  the  temperature  of  the  cooling  water;  the  back 
pressure  and  pressure  or  temperature  (both  if  practic- 
able) in  condenser. 

UNIT  OF  REFRIGERATING  CAPACITY. 

In  accordance  with  some  British  writers,  the  refrig- 
erating capacity  of  one  ton  of  melting  ice  is  equivalent 
to  318,080  thermal  units.  In  the  United  States  284,000 
thermal  units  are  allowed  to  be  equivalent  to  one  ton  of 
refrigerating  capacity,  or  to  the  refrigerating  capacity  of 
one  ton  of  melting  ice.  This  disagreement  is  due  to  the  dif- 
ferent amount  of  ice  which  is  taken  to  make  up  a  ton. 
In  the  former  case  2,240  pounds  are  calculated  per  ton, 
and  in  the  latter  only  2,000  pounds  are  allowed  per  ton. 

TEST  OF  OTHER  MACHINES. 

The  testing  of  other  refrigerating  machines,  such  as 
are  operated  with  sulphurous  acid,  carbonic  acid,  Pictet's 
liquid,  etc.,  can  be  performed  on  the  same  lines  as  that 
of  the  ammonia  compression  machine.  A  similar  course 
also  applies  in  the  case  of  air  compression,  vacuum  ma- 
chines and  other  devices,  the  principal  question  always 
being  as  to  what  amount  of  coal  or  power  and  of  cooling 
water  is  required  to  produce  a  certain  amount  of  refrig- 
eration. In  comparing  the  efficiency  of  machines  in 
different  localities  due  allowance  must  always  be  made 
for  differences  in  the  water  supply,  its  temperature,  its 
accessibility  and  available  quantity. 


APPENDIX  I. 

APPENDIX  I.— TABLES,  ETC. 


309 


Area  of 
Area  of 
Area  of 
Area  of 
Area  of 

Area  of 
Area  of 

Area  of 
Area  of 


MENSURATION. 
MENSURATION  OF  SURFACES. 

any  parallelogram =  base  X  perpendicular  height. 

any  triangle  .  ..  =  base  X  y2  perpendicular  height. 

any  circle =  diameterz  x  .7854. 


sector  of  circle =  arc  X  yz  radius. 

segment  of  circle =  area  of  sector  of  equal  radius, 

less  area  of  triangle . 

parabola =  base  X  %  height. 

ellipse =  longest  diameter  X  shortest  di- 
ameter X  .7864. 

cycloid =  area  of  generating  circle  X  3. 

s.ny  regular  polygon...  =  sum  of  its  sides  X  perpendicular 
from  its  center  to  one  of  its 
sides  +  2. 

Surface  of  cylinder =  area  of    both  ends  -f-  length  X 

circumference. 

Surface  of  cone =»  area  of  base  -f  circumference  of 

base  X  yz  slant  height. 

Surface  of  sphere •=  diameterz  X  3. 1415. 

Surface  of  frustum =  sum  of  girth  at  both  ends  X  14 

slant  height  +  area  of  both 
ends. 

Surface  of  cylindrical  ring =  thickness  of  ring  added  to  the 

inner    diameter    X  by    the 
thickness  X  9. 8698. 

Surface  of  segment =  height  of   segment  X  by  whole 

circumference  of  sphere  of 
which  it  is  a  part. 

POLYGONS. 

1.  To  find  the  area  of  any  regular  polygon:   Square 
one  of  its  sides,  and  multiply  said  square  by  the  number 
in  first  column  of  the  following  table. 

2.  Having  a  side  of  a  regular  polygon,  to  find  the 
radius  of  a  circumscribing  circle:    Multiply  the  side  by 
the  corresponding  number  in  the  second  column. 

3.  Having  the  radius  of  a  circumscribing  circle,  to 
find  the  side  of  the  inscribed  regular  polygon:    Multiply 
the  radius  by  the  corresponding  number  in  third  column. 


Num- 

1 

3 

3 

Angle  con- 

ber 

Name  of 

Area 

Radius 

Side 

tained 

of 

Polygon. 

=  S*X 

=  SX 

=  RX 

between 

Sides. 

two  sides. 

3 

I     Equila-    | 
•1       teral      J- 

.433 

.5774 

1.732 

60° 

f  Triangle.  ) 

4 

Square  

1. 

.7071 

1.4142 

90° 

5 

Pentagon.  . 

1.7205 

.8507 

1.1756 

108° 

6 

Hexagon..  . 

2.5891 

1. 

1. 

120° 

7 

Heptagon.  . 

B.6339 

1.1524 

.8678 

128.57° 

8 

Octagon  .  .  . 

4  8284 

1.3066 

.7654 

135° 

9' 

Nonagon.... 

6  !  1818 

1.4619 

.684 

140° 

10 

Decagon  — 

7.6942 

1.618 

.618 

144° 

11 

Undecagon.. 

9.3656 

1.7747 

.5635 

147.27° 

12 

Dodecagon  . 

11.1962 

1.9319 

.5176 

150° 

In  the  heads  of  the  columns  in  above  table,  S  =  side, 
and  B  =  radius . 


310 


MECHANICAL  REFRIGERATION. 


PROPERTIES  OF  THE  CIRCLE. 

Diameter    X    3.14159  =  circumference. 
Diameter    X      .8862    =  side  of  an  equal  square. 
Diameter    X      .7071    =  side  of  an  inscribed  square. 
Diameters  X      .7854    =  area  of  circle. 
Radius        X    6.28318  =  circumference, 
Circumference  -4-  3.14159  =  diameter. 

The  circle  contains  a  greater  area  than  any  plane 
figure  bounded  by  an  equal  perimeter  or  outline. 

The  areas  of  circles  are  to  each  other  as  the  squares 
of  their  diameters. 

Any  circle  whose  diameter  is  double  that  of  another 
contains  four  times  the  area  of  the  other. 

Area  of  a  circle  is  equal  to  the  area  of  a  triangle  whose 
base  equals  the  circumference,  and  perpendicular  equals 
the  radius. 


MENSURATION  OF  SOLIDS. 


Cylinder 


area  of  one  end  X  length, 


Sphere =  cube  of  diameter  X  .5236. 

Segment  of  sphere '. . . .  =  square  root  of  the  height  added  to 

three  times  the  square  of  radius 
of  base  X  height  and  .5236. 
=  area    of   base  X  ya   perpendicular 

height. 

=  product  of  diameter  of  both  ends 
4-  sum  of  their  squares  X  per- 
pendicular height  X  .2618. 
=  sum  of  the  areas  of  the  two  ends  + 
square  root  of  their  product,  X 
%  of  the  perpendicular  height. 

Solidity  of  a  wedge =  areaof  base  X  ya  perpendic'r  height. 

Frustum  of  a  weage =  Vi  perpendicular  height  X  sum  of 

the  areas  of  the  two  ends. 

Solidity  of  a  ring =  thickness    +    inner    diameter,    X 

square  of  the  thickness  X  2.4674. 

POLYHEDRONS. 


Cone  or  pyramid 

Frustum  of  a  cone 

Frustum  of  a  pyramid. 


1 

8 

3 

4 

Radius  of 

Radius  of 

No. 

Names 

Circum- 

Inscribed 

Area  of 

Cubic 

of 

scribed 

Circle. 

Surface. 

Contents. 

Sides 

Circle. 

R=SX 

R=  SX 

A=  S2  X 

C=  S3X 

4 

Tetrahedron... 

.6124 

.2041 

1.7320 

.1178 

6 

Hexahedron... 

.866 

.5 

6. 

1. 

8 

Octahedron  — 

.7071 

.4082 

3.4641 

.4714 

12 

Dodecahedron 

1.4012 

1.1135 

20.6458 

7.6631 

20 

Icosahedron  .  .  . 

.951 

.7668 

86.602 

2.1817 

Side  is  length  of  linear  edge  of  any  side  of  the  figure. 

1.  Radius  of  circumscribed  circle  =  side  multiplied 
by  the  number  in  first  column  corresponding  to  figure. 

2.  Radius  of  inscribed  circle  =  side  multiplied  by  the 
number  in  second  column  corresponding  to  figure. 

3.  Area  of  surface  =  square  of  side  multiplied  by  the 
number  in  third  column  corresponding  to  figure. 

4.  Cubic  contents  =  cube  of  side  multiplied  by  num- 
ber ifj  fourth  column  corresponding  to  figure, 


APPENDIX  1. 


311 


TABLE  OF  AMMONIA  GAS  ( SUPER-HEATED  VAPOR). 
Temperature  in  Degrees  F. 


M 

0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

Number  of  Cu.  Ft.,v,  Approximately  Contained  in  ILb.  of  Gas. 


15 

18.81 

19.05 

19.20 

19.48 

19.68 

19.87 

20.08 

20.25 

20.544 

20.74 

16 

17.56 

17.85 

18.09 

18.24 

18.43 

18.52 

18.81 

18.90 

19.20 

19.44 

17 

16.60 

16.70 

16.96 

17.08 

17.28 

17.48 

17.66 

17.85 

18.09 

18.31 

18 

15.54 

15.84 

15.93 

16.12 

16.32 

16.51 

16.70 

16.89 

17.08 

17.32 

19 

14.78 

14.97 

15.16 

15.26 

15.45 

15.64 

15.84 

15.93 

16.12 

16.36 

20 

14.01 

14.25 

14.40 

14.49 

14.68 

14.88 

14.97 

15.16 

15.36 

15.58 

21 

13.34 

13.53 

13.63 

13.82 

14.01 

14.11 

14.30 

14.40 

14.59 

14.80 

22 

12.76 

12.86 

13.05 

13.15 

1334 

13.44 

13.63 

13.72 

13.92 

14.12 

23 

12.19 

12.28 

12.48 

12.57 

12.76 

12.86 

13.05 

13.15 

13.34 

13.54 

24 

11.71 

11.80 

11.90 

12.09 

12.19 

12.38 

12.48 

12.57 

12.76 

12.96 

25 

11.23 

11.34 

11.42 

11.61 

11.71 

11.80 

11.90 

12.09 

12.19 

12.38 

26 

10.75 

10.84 

11.04 

11.13 

11.23 

11.32 

11.62 

11.61 

11.71 

11.85 

27 

10.36 

10.46 

10.56 

10.75 

10.84 

10.94 

11.04 

11.23 

11.32 

11.45 

28 

9.98 

10.08 

10.17 

10.36 

10.46 

10.56 

10.65 

10.75 

10.84 

10.94 

29 

9.60 

9.69 

9.79 

9.98 

10.08 

10.17 

10.27 

10.36 

10.46 

10.57 

30 

9.2120 

9.30 

10.46 

9.60 

9.69 

9.79 

9.98 

10.08 

10.17 

10.27 

31 

8.84 

9.12 

9.21 

9.31 

9.40 

9.50 

9.60 

9.69 

9.80 

9.91 

32 

8.83 

8.93 

9.02 

9.12 

0.21 

9.31 

9.40 

9.50 

9.61 

33 

8.54 

8.64 

8.73 

8.83 

8.91 

9.02 

9.11 

9.21 

9.31 

34 

8.25 

9.35 

8.49 

8.54 

8.64 

8.73 

8.83 

8.92 

9.02 

35 

8.16 

8.25 

8.35 

8.44 

8.54 

8.64 

8.64 

8.75 

36 

7.87 

7.96 

8.06 

8.16 

8.26 

8.35 

8.44 

8.65 

37 

7.68 

7.67 

7.87 

7.96 

8.06 

8.16 

8.26 

8.36 

38 

7.48 

7.58 

7.68 

7.77 

7.77 

7.87 

7.96 

8.05 

39 

7.39 

7.48 

7.48 

7.58 

7.68 

7.77 

7.87 

40 

7.20 

7.29 

7.39 

7.39 

7.48 

7.58 

7.68 

41 

7.00 

7.10 

7.20 

7.20 

7.29 

7.39 

7.49 

42 

6.81 

6.91 

7.00 

7.10 

7.10 

7.20 

7.30 

43 

6.72 

6.81 

6.91 

7.00 

7.08 

7.16 

44 

6.52 

6.62 

6.72 

6  81 

6.91 

7  10 

45 

6.43 

6.52 

6.62 

6.62 

6.72 

4  .  J.U 

6.82 

312 


MECHANICAL  REFRIGERATION. 


SQUARE  ROOTS   AND   CUBE  ROOTS  OF  NUMBERS. 
FROM  1  TO  20. 


No 

Sq. 

Cube. 

Sq.  Rt 

C.Rt. 

No 

Sq.  Rt 

C.Rt 

No 

Sq.  Rt 

C.Rt. 

.1 

.01 

.001 

.316 

.464 

. 

2.098 

1.639 

.5 

3.240 

2.189 

.15 

.023 

.003 

.387 

.531 

.'{ 

2.121 

1.651 

.( 

3.256 

2.197 

.2 

.04 

.008 

.447 

.585 

.( 

3.145 

1.663 

tj 

3.271 

2.204 

.25 

.063 

.016 

.500 

.630 

r 

2.168 

1.675 

.( 

3.286 

2.211 

.3 

.09 

.027 

.548 

.669 

A 

2.191 

1.687 

.9 

3.302 

2.217 

.35 

.123 

.043 

.592 

.705 

.9 

2.214 

1.699 

11.0 

3.317 

2.224 

.4 

.16 

.064 

.633 

.737 

5.0 

2.236 

1.710 

.1 

3.332 

2.231 

.45 

.203 

.091 

.671 

.766 

.1 

2.258 

1.721 

c 

3.347 

2.237 

.5 

.25 

.125 

.707 

.794 

f 

2.280 

1.733 

.'? 

3.362 

2.244 

..55 

.303 

.166 

.742 

.819 

'.i 

2.302 

1.744 

.4 

3.376 

2.251 

.6 

.36 

.216 

.775 

.843 

.4 

2.324 

1.754 

g 

3.391 

2.257 

.65 

.423 

.275 

.806 

.866 

g 

2.345 

1.765 

.'e 

3.406 

2.264 

.7 

.49 

.343 

.837 

.888 

'.6 

2.366 

1.776 

.7 

3.421 

2.270 

.75 

.563 

.422 

.866 

.909 

.7 

2.388 

1.78"6 

.8 

3.435 

2.277 

.8 

.64 

.512 

.894 

.928 

.8 

2.408 

1.797 

.9 

3.450 

2.283 

.85 

.723 

.614 

.922 

.947 

.9 

2.429 

1.807 

12.0 

3.464 

2.289 

.9 

.81 

.729 

.949 

.965 

6.0 

2.450 

1.817 

.1 

3.479 

2.296 

.95 

.903 

.857 

.975 

.983 

.1 

2.470 

1.827 

.2 

3.493 

2.302 

1. 

1.000 

1.000 

1.000 

1.000 

.2 

2.490 

1.837 

.3 

3.507 

2.308 

.05 

1.103 

1.158 

1.025 

1.016 

.3 

2.510 

1.847 

.4 

3.521 

2.315 

1.1 

1.210 

1.331 

1.049 

1.032 

.4 

2.530 

1.857 

.5 

3.536 

2.321 

.15 

1.323 

1.521 

1.072 

1.048 

.5 

2.550 

1.866 

.6 

3.550 

2.327 

1.2 

1.440 

1.728 

1.095 

1.063 

.6 

2.569 

1.876 

.7 

3.564 

2.333 

.25 

1.563 

1.953 

1.118 

1.077 

.7 

2.588 

1.885 

.8 

3.578 

2.339 

.3 

1.690 

2.197 

1.140 

1.091 

.8 

2.608 

1.895 

.9 

3.592 

2.345 

1.35 

1.823 

2.460 

1.162 

.105 

.9 

2.627 

1.904 

13.0 

3.606 

2.351 

1.4 

1.960 

3.744 

1.183 

.119 

7.0 

2.646 

1.913 

.2 

3.633 

2.363 

.45 

2.103 

3.049 

1.204 

1.132 

.1 

2.665 

..922 

.4 

3.661 

2.375 

1.5 

2.250 

3.375 

1.225 

1.145 

.2 

2.683 

1.931 

.6 

3.688 

2.387 

.55 

2.403 

3.724 

1.245 

1.157 

.3 

2.702 

.940 

.8 

3.715 

2.399 

1.6 

2.560 

4.096 

1.265 

1.170 

.4 

2.720 

1.949 

14.0 

3.742 

2.410 

.65 

2.723 

4.492 

1.285 

.182 

.5 

2.739 

1.957 

.2 

3.768 

2.422 

1.7 

2.890 

4.913 

1.304 

.194 

.6 

2.757 

1.966 

.4 

3.795 

2.433 

.75 

3.063 

6.359 

1.323 

1.205 

.7 

2.775 

1.975 

.6 

3.821 

2.444 

1.8 

3.240 

5.832 

1.342 

.216 

.8 

2.793 

1.983 

.8 

3.847 

2.455 

.85 

3.423 

6.332 

1.360 

.228 

.9 

2.811 

1.992 

15.0 

3.873 

2.466 

1.9 

3.610 

6.859 

1.378 

.239 

8.0 

2.828 

2.000 

.2 

3.899 

2.477 

.95 

3.803 

7.415 

1.396 

.249 

.1 

2.846 

2.008 

.4 

3.924 

2.488 

2.0 

4.000 

8  000 

1.414 

1.260 

.2 

2.864 

2.017 

.6 

3.950 

2.499 

.1 

4.410 

9.261 

1.449 

.281 

.3 

2.881 

2.025 

.8 

3.975 

2.509 

2 

4.840 

10.65 

1.483 

.301 

.4 

2.898 

2.033 

16.0 

4-000 

2.520 

'.3 

5.290 

12.17 

1.517 

.320 

.5 

2.916 

2.041 

.2 

4.025 

2.530 

.4 

5.760 

13.82 

1.549 

1.339 

.6 

2.933 

2.049 

.4 

4.050 

2.541 

.5 

6.250 

15.63 

1.581 

.357 

.7 

2.950 

2.057 

.6 

4.074 

2.551 

.6 

6.760 

17.58 

1.613 

.375 

.8 

2.967 

2.065 

.8 

4.099 

2.5(51 

.7 

7.290 

19.68 

1.643 

.393 

.9 

2.983 

2.072 

17.0 

4.123 

2.571 

.8 

7.840 

21.95 

1.673 

.409 

9.0 

3.000 

2.080 

.2 

4.147 

2.581 

.9 

8.410 

24.39 

1.703 

.426 

.1 

3.017 

2.088 

.4 

4.171 

2.591 

3.0 

9.00 

27.00 

1.732 

.442 

.2 

3.033 

3.095 

.6 

4.195 

2.601 

.1 

9.61 

29.79 

1.761 

.458 

.3 

3.050 

2.103 

.8 

4.219 

2.611 

.2 

10.24 

32.77 

1.789 

.474 

.4 

3.066 

2.111 

18.0 

4-243 

2.621 

.3 

10.89 

35.94 

1.817 

.489 

.5 

3.08-2 

2.  118 

.2 

4.266 

2.630 

.4 

11.56 

39.30 

1.844 

.504 

.6 

3.098 

2.125 

.4 

4.290 

2.640 

.5 

12.25. 

42.88 

1.871 

.518 

.7 

3.115 

2.133 

.6 

4.313 

2.650 

.6 

2.96 

46.66 

1.897 

1.533 

.8 

3.131 

2.140 

.8 

4.336 

2.659 

.7 

13.69 

50.65 

1.924 

1.547 

.9 

3.146 

2.147 

19.0 

.359 

2.6(58 

.8 

14.44 

54.87 

1.949 

1.561 

10.0 

3.162 

2.154 

.2 

.382 

2.678 

.9 

^5.21 

59.32 

3.975 

.574 

.1 

3.178 

2.164 

.4 

.405 

2.687 

4.0 

16.00 

64.00 

2.000 

..587 

.2 

3.194 

2.169 

.6 

.427 

2.696 

.1 

16.81 

68.92 

2.025 

1.601 

.3 

3.209 

2.177 

.8 

.450 

2.705 

.2 

17.64 

74.09 

2.049 

1.613 

.4 

3.225 

2.183 

20.0 

.472 

2.714 

.3 

18.49 

79.51 

2.074 

1.626 

APPENDIX  I. 


313 


TABLE  OF  SQUARES,  CUBES,  SQUARE    ROOTS   AND   CUBE 
ROOTS  OF  NUMBERS  FROM  1  TO  100. 


2 

£ 

No. 

§ 

Cube. 

Sq.  Rt. 

C.Rt. 

No. 

c$ 
2 

Cube. 

Sq.  Rt. 

0.  Rt. 

gl. 

£ 

1 

i 

1 

1.0000 

.0000 

51 

2601 

132651 

7.1414 

3.7084 

2 

4 

8 

1.4142 

.2599 

52 

2704 

140608 

7.2111 

3.7325 

3 

9 

27 

1.7321 

.4422 

53 

2809 

148877 

7.2801 

3.7563 

4 

16 

64 

2.0000 

.5874 

54 

2916 

157464 

7.3485 

3.7798 

5 

25 

125 

2.2361 

.7100 

55 

3025 

166375 

7.4162 

3.8030 

6 

36 

216 

2.4495 

1.  8171 

56 

3136 

175616 

7.4833 

3.8259 

7 

49 

343 

2.6458 

1.9129 

57 

3249 

185193 

7.5498 

3.8485 

8 

64 

512 

2.8284 

2.0000 

58 

3364 

195112 

7.6158 

3.8709 

9 

8i 

729 

3.0000 

2.0801 

59 

3481 

205379 

7.6811 

3.8930 

10 

100 

1000 

3.1623 

2.1544 

60 

3600 

216000 

7.7460 

3.9149 

11 

121 

1331 

3.3166 

2.2240 

61 

3721 

226981 

7.8102 

3.9365 

12 

144 

1728 

3.4641 

2.2894 

62 

3844 

238328 

7.8740 

3.  9579 

13 

169 

2197 

3.6056 

2.3513 

63 

3969 

250047 

7.9373 

3.9791 

14 

196 

2744 

3.7417 

2.4101 

64 

4096 

262144 

8.0000 

4.0000 

16 

225 

3375 

3.8730 

2.4662 

66 

4225 

274625 

8.0623 

4.0207 

16 

256 

4096 

4.0000 

2.5198 

66 

4356 

287496 

8.1240 

4.0412 

17 

289 

4913 

4.1231 

2.5713 

67 

4489 

300764 

8.1854 

4.0615 

18 

324 

5832 

4.2426 

2.6207 

68 

4624 

314432 

8.2462 

4.0817 

19 

361 

6859 

4.3589 

2.6684 

69 

4761 

328509 

8.3066 

4.1016 

20 

400 

8000 

4.4721 

2.7144 

70 

4900 

343000 

8.3666 

4.1213 

21 

441 

9261 

4.5826 

2.7589 

71 

5041 

357911 

8.4261 

4.1408 

22 

484 

10648 

4.6904 

2.8020 

72 

5184 

373248 

8.4853 

4.1602 

23 

529 

12167 

4.7958 

2.8429 

73 

5329 

389017 

8.5440 

4.  1793 

24 

576 

13824 

4.8990 

2.8845 

74 

5476 

405224 

8.6023 

4.1983 

25 

625 

15625 

5.0000 

2.9240 

75 

5625 

421875 

8.6603 

4.2172 

26 

676 

17576 

5.0990 

2.9625 

76 

5766 

438976 

8.7178 

4.2358 

27 

729 

19683 

5.1962 

3.0000 

77 

5929 

456633 

8.7750 

4.2543 

28 

784 

21952 

5.2915 

3.0366 

78 

6084 

474552 

8.8318 

4.2721 

29 

841 

24389 

5.3852 

3.0723 

79 

6241 

493039 

8.8882 

4.2908 

30 

900 

27000 

5.4772 

3.1072 

80 

6400 

512000 

8.9443 

4.3089 

31 

961 

29791 

5.5678 

3.1414 

81 

6561 

531441 

9.0000 

4.3267 

32 

1024 

32768 

5.6569 

3.1748 

82 

6724 

551368 

9.0654 

4.3445 

33 

1089 

35937 

5.7446 

3.2075 

83 

6889 

571787 

9.1104 

4.3621 

34 

1156 

39304 

5.8310 

3.2396 

84 

7056 

592704 

9.1652 

4.3795 

35 

1225 

42875 

5.9161 

3.2711 

85 

7225 

614125 

9.2195 

4.3968 

36 

1296 

46656 

6.0000 

3.3019 

86 

7396 

636056 

9.2736 

4.4140 

37 

1369 

f0653 

6.0828 

3.3322 

87 

7569 

658503 

9.3274 

4.4310 

38 

1444 

54872 

6.1644 

3.  3620 

88 

7744 

681472 

9.3808 

4.4480 

39 

1521 

59319 

6.2450 

3.3912 

89 

7921 

704969 

9.4340 

4.4647 

40 

1600 

64000 

6.3246 

3.4200 

90 

8100 

729000 

6.4868 

4.4814 

41 

1681 

68921 

6.4031 

3.4482 

91 

8281 

753571 

9.5394 

4.4979 

42 

1764 

74088 

6.4807 

3.4760 

92 

8464 

778688 

9.5917 

4.5144 

43 

1849 

79507 

6.5574 

3.5034 

93 

8649 

804357 

9.6437 

4.5307 

44 

1936 

85184 

6.6332 

3.5303 

94 

8836 

830584 

9.6954 

£5488 

45 

2025 

91125 

6.7082 

3.5569 

95 

9025 

857375 

9.7468 

4.5629 

46 

2116 

97336 

6.7823 

3.5830 

96 

9216 

884736 

9.7980 

4.5789 

47 

2209 

103823 

6.8557 

3.6088 

97 

9409 

912673 

9.8489 

4.5947 

48 

2304 

110592 

6.9282 

3.6342 

98 

9604 

941192 

9.8995 

4.6104 

49 

2401 

117649 

7.0000 

3.6563 

99 

9801 

970299 

9.9499 

4.6261 

50 

2500 

125000 

7.0711 

3.6840 

100 

10000 

1000000 

10.0000 

4.6416 

314  MECHANICAL  REFRIGERATION. 

AREAS  OF  CIRCLES — ADVANCING  BY  EIGHTHS. 


a 

cS 

a 

0 

K 

K 

% 

X 

% 

% 

% 

0 

.0 

.01 

.05 

.11 

.19 

.30 

.44 

.60 

1 

.785 

.99 

1.22 

1.48 

1.76 

2.07 

2.40 

2.76 

2 

3.14 

3.54b 

3.97 

4.43 

4.90 

5.41 

5.93 

6.49 

3 

7.068 

7.66 

8.29 

8.94 

9.62 

10.32 

11.04 

11.79 

4 

12.56 

13.36 

14.18 

15.03 

15.90 

16.80 

17.72 

18.66 

5 

19.63 

20.62 

21.64 

22.69 

23.75 

24.85 

25.96 

27.18 

6 

28.27 

29.46 

30.67 

31.91 

33.18 

34.47 

35.78 

37.12 

7 

38.48 

39.87 

41.28 

42.71 

44.17 

45.66 

47.17 

48.70 

8 

50.29 

51.84 

53.45 

55.08 

56.74 

58.42 

60.13 

61.86 

9 

63.61 

65.39 

67.20 

69.02 

70.88 

72.75 

74.69 

76.58 

10 

78.54 

80.51 

82.51 

84.54 

86.59 

88.66 

90.76 

92.88 

11 

95.03 

97.20 

99.40 

101.6 

103.8 

106.1 

108.4 

110.7 

12 

113.0 

115.4 

117.8 

120.2 

122.7 

125.1 

127.6 

130.1 

13 

132.7 

135.2 

137.8 

140.5 

143.1 

145.8 

148.4 

151.2 

J4 

153.9 

156.6 

159.4 

162.2 

165.1 

167.9 

170.8 

173.7 

15 

176.7 

179.6 

182.6 

185.6 

188.6 

191.7 

194.8 

197.9 

16 

201.0 

204.2 

207.3 

210.5 

213.8 

217.0 

220.3 

223.6 

17 

226.9 

230.3 

233.7 

237.1 

240.5 

243.9 

247.4 

250.9 

18 

254.4 

258.0 

261.5 

265.1 

268.8 

272.4 

276.1 

279.8 

19 

283.5 

287.2 

291.0 

294.8 

298.6 

302.4 

306.3 

310.2 

20 

314.1 

318.1 

322.0 

326.0 

330.0 

334.1 

338.1 

342.2 

21 

346.3 

350.4 

354.6 

358.8 

363.0 

367.2 

371.5 

375.8 

22 

380.1 

384.4 

388.8 

393.2 

397.6 

402  0 

406.4 

410.9 

23 

415.4 

420.0 

424.5 

429.1 

433.7 

438.3 

433.0 

447.6 

24 

452.3 

457.1 

461.8 

466.6 

471.4 

476.2 

481.1 

485.9 

25 

490.8 

495.7 

500.7 

505.7 

510.7 

515.7 

520.7 

525.8 

26 

530.9 

536.0 

541.1 

546.3 

551.5 

556.7 

562.0 

667.2 

27 

572.5 

577.8 

583.2 

588.5 

593.9 

599.3 

604.8 

610.2 

28 

615.7 

621.2 

626.7 

632.3 

637.9 

643.5 

649.1 

654.8 

29 

660.5 

666.2 

671.9 

677.7 

683.4 

689.2 

695.1 

700.9 

30 

706.8 

712.7 

718.6 

724.6 

730.6 

736.6 

742.6 

748.6 

31 

754.8 

760.9 

767.9 

773.1 

779.3 

785.5 

791.7 

798.0 

32 

804.3 

810.6 

816.9 

823.2 

829.6 

836.0 

842.4 

848.8 

33 

855.3 

861.8 

868.3 

874.9 

881.4 

888.0 

894.6 

901.3 

34 

907.9 

914.7 

921.3 

928.1 

934.8 

941.6 

948.4 

955.3 

35 

962.1 

969.0 

975.9 

982.8 

989.8 

996.8 

003.  & 

010.8 

36 

017.9 

025.0 

032.1 

039.2 

046.3 

053.5 

060.7 

068.0 

37 

075.2 

082.5 

089.8 

097.1 

104.5 

111.8 

119.2 

126.9 

38 

134.1 

141.6 

149.1 

156.6 

164.2 

171.7 

179.3 

186.7 

39 

194.6 

202.3 

210.0 

217.7 

225.4 

233.2 

241.0 

248.8 

40 

256.6 

L264.5 

272.4 

L280.3 

1288.2 

296.2 

304.2 

312.2 

41 

320.3 

328.3 

336.4 

344.5 

352.7 

360.8 

369  0 

377.2 

42 

385.4 

393.7 

402.0 

410.3 

418.6 

427.0 

435.4 

443.8 

43 

452.2 

460.7 

469.1 

477.6 

486.2 

4!)4.7 

503.3 

511.  9 

44 

520.5 

529.2 

537.9 

546.6 

555.3 

564.0 

572.8 

581.6 

45 

590.4 

599.3 

608.2 

617.0 

626.0 

634.9 

643.9 

652.9 

EQUIVALENTS  OF  FRACTIONS  OF  AN  INCH. 


Fractions  of 
an  Inch. 

Decimals  of 
Foot. 

Fractions  of 
an  Inch. 

Decimals  of 
Foot. 

H 

.0104 
.0208 
.0313 
.0417 

5/B 

\ 

.0521 
.0625 
.0729 
.0833 

APPENDIX  I. 
TABLE  OF  LOGARITHMS. 


315 


H703 

04139  04532J04921  05307J05690 
13  07918  08278  08636  08990  09342 


16  20412  20682  20951  21218  21484 

17  23045  23299  23552  23804  24054 
IB  25527  25767  26007  26245  26481 

19  27875  28103  28330  28555  28780 

20  30103  30319^0535,30749  30963 
"21  32222  32428132633  32838  33041 


22  34242  34439  34635  34830  35024  35218  35410  35602  35793  35983 


23  36172  36361 

24  38021  38201 


25  39794  39967  40140  40312  40483  40654  40824 


264149741664 


27  43136  48297  43457  43616  43775  43933  44091  44248  44404  44560  158 


3 


00000  30103  47712  60206  69897  77815  84510  90309  95424 


11394 


11727 


17609 


17897 


1205712385 


14613  14922  15228  15533 


18184 


1271013033:13353  13672 


15836 


1846918752 


38381 


36548  36735  36921 


38560  38739  38916  39093  39269  39445139619 


41830  41995  42160  42324  42488  42651 


28  44716  44870  45025  45178  45331 

29  46239  46389  46538  46686  46834 
30 .47712  47856  48000  48144  48287 

31  49136  49276  49415  49544  49693 

32  50515  50650  50785  50920  51054 

33  51851  51982  52113  52244  52374 

34  53148  53275  53402  53529  5365 


35  54406  54530  54654  54777  54900  55022j55145  5 

36  55630  55750i55870l55990  56110 

37  56820  56937K 


|6.1066'61172 

J62117  62221 

42  6^325;62428!6253l!62634|62736  62838  62941  63042(63144  63245 


33  63346  63447j63548'63648  63749  63849  63948  64048  64147  64,246 
.44  64345'64443'64542'64640  64738  64836  64933  65030  65127  65224 
45  65321  !65417|65513!65609  65705  65801  65896  65991 
'46  66275:66370  66464i66558'66651  66745  66838  66931 
47  67209 167302 1 67394  67486:67577  67669  67760  67.851 


66086,6,6181 
6702467'!  17 
6794268033 

48  68124!68214!68304[68894:68484  68574  68663  68752  68842|68931 
JI69284 

50  69897J69983!  70070  701 56i  70243  70329 


49  69019  69108!69106;69284  69372  69460  69548  69635  69723169810 
70243  70329  70415  70500  70588170671 
71096  7118Q171265  71349J71433[71516 
71933  72015  72098  72181 172263F72345 


70757!  70842i  70927  71011 
527160071683 


53  72427  72509  72591 


71767  71850  71933  72015  72098  72181 


72672  72754 


73319  73899  73480J73560  73639  73719  73798173878)73957 


61 
52 
53 
54 
55i74036l74115l74194i74272  74351  74429  74507 

56  74818  74896  74973  75050  75128 

57  75587  75663l75739;75815  75891 

58  76342  76417(76492  76566  76641 

59  77085  771 581 77332  77305  77378  77451 


8  74896  74973  75050  75128  75204  75281 
t?  ?Mtftftl7.17ftfii7fifiin  75891  75960  76042 


•eO[77815l77887i77959|78031 


02119  02530  02938  03342  03742  415 


06069  06445  06818  07188  07554 


09691110037 


16136:16435 
1903319312 
21748  2201 G  22271 
24303|24551 
26717126951 
29003J  29225 


37106  37291 


11059344 


379 
344 
323 


10380  10721 

13987|  14301 
16731 

1959019865120139281 
2227 122531 1 22788  26$ 
247972504225285249 
27184J27415127646234 
29446;29666i29885  222 
31175(31386' 31597j31806;32014  212 
33243  33445  33646  33845J34044  202 


37474 


45484  45636  45788  45939  46089  153 


37657j37839  185 


409934116241330170 
4281342975 


46982  47129  47275  47421 


47681 


48430  48572  48713  48855  48995 
49831  49968  50106  50242  50379 
51188I51321  51454  51587  51719  134 
52504:52634  52763  52891  53020  130 
53782!53907  54033  54158  54282  126 
55022  55145  55266  55388,55509  122 
56229  56348  56466  56584;56702  119 

17518  57634  57749157863  116 
'5888358995113 


61278;6i~384i61489;61595:61700  61804  61909  62013162117  62221 


76715 


77524 
78103  78175  78247 


72835  72916  72997  78078  78168 

73639  73719  73798l73878l73957 


745857466374741 
753587543475511 
761177619276267 


76789  76863)76937  77011 

•™eo"  77597)77670  77742 
7831 8!  78390!  78461 


193 

185 
177 
170 
164 


148 
143 
138 


316 


MECHANICAL  REFRIGERATION. 
TABLE  OF  LOGARITHMS. 


1 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

! 

61 

78533 

78604 

78675 

78746 

78816 

78887 

78958 

79028 

79098 

79169 

^ 

62 

79239 

79309  79379  79448 

79518 

79588 

79657 

79726 

79796 

79865 

70 

63 

79934 

800038007180140 

80208 

80277 

80345 

80414 

80482 

80550 

69 

64 

80618 

80685807538082180888 

80956 

81023 

81090 

81157 

81224 

68 

65 
66 

81291 
81954 

81358l81424'8149l  81557 
82020:82085  82151  82216 

81624 

82282 

81690 

82347 

81756 
82412 

81822 
82477 

81888 
82542 

67 
66 

67 
68 

82607  82672J82737  82801 
83251  183314  83378  83442 

82866 
83505 

82930 
83569 

82994 
83632 

83058 
83695 

83123 

83758 

83187 

83822 

64 
63 

69 

70 

83885  83947  84010  84073 
84509  84571,84633  84695 

84136 
84757 

84198 
84819 

84261 
84880 

84323 
84942 

84385  84447 
85003|  85064 

6 
62 

71 

85125 

85187 

85248 

85309 

85369 

85430 

85491 

85552'85612 

85673 

61 

72 

85733 

85793 

86853 

85913 

85973 

86033 

86093 

86153  86213 

86272 

€0 

73 

86332 

86*91 

864-51 

86510 

86569 

86628 

86687 

86746  86805 

86864 

69 

74 

86923 

86981 

87040 

87098 

87157 

87215 

87273 

87332  87390 

87440 

58 

75 

8750(3 

87564 

87621 

87679 

87737 

87794 

87852 

87909 

87967 

88024 

57 

76 

88081 

88138 

88195 

88252 

88309 

88366 

88422 

88479  88536 

88592 

57 

77 

88649 

88705 

88761 

888  IN 

88874 

88930 

88986 

89043 

89098 

89153 

56 

78 

89209 

89265 

89320 

89376 

89431 

89487 

89542 

89597 

89652 

89707 

55 

79 

89762 

89817 

89872 

89927 

89982 

90036 

90091 

90145 

90200 

90254 

54 

80 

90309 

90363 

90417 

90471 

90525 

90579 

90633 

90687 

90741 

90794 

54 

81 

90848 

90902 

90955 

91009 

91062 

91115 

91169 

91222 

91275 

91328 

53 

82 
83 

91381 
91907 

91434 
91960 

91487 
92012 

91540 
92064 

91592 
92116 

91645 
92168 

91698 
92220 

9175091803 
92272!92324 

91855 
92376 

53 
52 

84 

92427 

92479 

92531 

92582 

92634 

92685 

92737. 

92788;92839 

92890 

51 

85 

£2942 

92993 

93044 

93095 

93145 

93196 

93247 

93298  93348 

93399 

51 

86 

93449 

93500 

93550 

93601 

93651 

93701 

93751 

93802  93852 

93902 

50 

87193958 

94001 

94051 

94101 

94151 

94200 

94250 

94300  94349 

94398 

49 

.83 

94448 

94497 

94546 

94596 

94645 

94694 

94743 

94792  94841 

94890 

49 

89 

94939 

94987 

95036 

95085 

95133 

95182 

95230 

95279  95327 

95376 

48 

<JO 

95424 

95472 

95520 

95568 

95616 

95664 

95712 

95760 

95b08 

95856 

48 

91 

95904 

95951 

95999 

96047 

96094 

96142 

96189 

96237 

96284 

96331 

48 

92 

96378 

9.6426 

96473 

96520 

96567 

96614 

96661 

96708  96754 

96801 

47 

93 
94 

96848 
97312 

96895 
97359 

96941 
97405 

96988 
97451 

97034 
97497 

97081 
97543 

97127 

97589 

9717497220 
9763597680 

97266 
97726 

47 
46 

95 

97772 

97818 

97863 

97909 

97954 

98000 

9804598091198136 

98181 

46 

90 

98227 

98272 

98317 

98362 

98407 

98452 

98497,9854298587 

98632 

45 

97 

98677 

98721 

98766 

98811 

98855 

98900 

98945198989  99034 

99078 

45 

98 

99122 

99167 

9921  1 

99255 

99299 

993439938799431 

99475 

99519 

44 

,99 

99563 

99607 

99651 

99695 

99738 

99782199826 

99869 

99913 

99956 

44 

I 

0 

1 

2 

3 

4 

5    6- 

7 

8 

9 

! 

By  the  use  of  these  tables  the  logarithm  of  any 
number  below  10,000  can  be  found  with  sufficient  accu- 
racy in  the  manner  exemplified  on  the  following  page, 
and  for  most  uses  it  will  be  found  equally  convenient 
as  many  much  more  extensive  tables. 


APPENDIX  1. 


317 


The  use  of  the  foregoing  table  i8  explained  by  the 
following  rules: 

RULES  FOR    LOGARITHMS. 

To  multiply  by  logarithms  add  the  logarithms  to- 
gether and  find  number  of  logarithms  so  found. 

To  divide  by  logarithms  subtract  one  from  the  other. 

To  extract  the  roots,  divide  the  logarithms  by  the 
index  of  the  root. 

To  raise  a  number  to  any  power,  multiply  the  logar- 
ithms by  the  index. 


Find  Log.  of  5065 

Log.  of  5060  =  3.70415 
Prop   86  x  Diff.  5  =          430 

Log.  required  =  3.704580 


Indices  of  Logarithms. 

Log.  4030     -3.60530 

403     =  2.60530 

49.3  - 1.60530 


3.771442 

••  3.770850 


Find  Number  of  Log. 
Log.  of  5900 


Diff.  592  -f-  Prop.  73-  8  Diff.  =  592 
No.  required  5908 


Log    4.03 
"        .403 


=  .60530 
=  T. 60530 
=  ^.60530 


Log.  nat.  n =2.3026  log.  n. 
WEIGHTS   AND  MEASURES. 


TROY  WEIGHT. 

24  grains  1  pennyweight:  dwt. 

20  pennyweights   1  ounce=480  grains. 

12  ounces  1  pound=240  dwts.=5,760  grains. 

AVOIRDUPOIS  OR  COMMERCIAL  WEIGHT. 

27.34375  grains  1  drachm. 

16  drachms  1  ounce=437.5  grains. 

16  ounces  1  pound— 256  drachms  =7,000  grains. 

28  pounds  1  quarter=448  ounces. 

4  quarters  1  cwt=112  pounds. 

20cwts.  lton=80  quarters  =2,240  Ibs. 

APOTHECARIES'  WEIGHT. 

20  grains       1  scruple     I     8  drachms  1  ounce. 
3  scruples.    1  drachm.    |    12  ounces     1  pound. 
The  grain  in  each  of  the  foregoing  tables  is  the  same. 
An  avoirdupois  pound  of  pure  water  has  the  following  volumes. 
At    32°  F. -.016021  cu.  ft.  or  27.684  cu.  ins. 
39.1°  "  =.016019    "     "     "  27.680    "      " 
62°     "=.016037    "    "     "  27.712    "     " 
212°    "  =.016770    "    "     "  28.978    "     " 

— D.  K.  Clark,  Rules,  Tables  and  Data. 

LONG  MEASURE. 

By  law  the  U.  S.  standards  of  length  and  weight  are  made  equal 
to  the  British. 

12  inches  1  foot. 

3  feet  1  yard  =  36  ins.  =  .9143919  metre. 

514  yards  1  rod,  pole  or  perch  —  16^  feet. 

40  rods  1  furlong. 

8  furlongs  1  mile  -  5,280  feet  -  63,360  ins. 

3  miles  1  league.     . 

A  palm  — 3  ins.     A  hand —  4  ins.    A  span  —  9  ins. 
A  fathom  =  6  f t.   A  cable's  length  -  120  fathoms. 
A  Gunter's  chain  is  66  ft.  long,  and  80  Gunter's  chains  —  1  mile 
In  the  U.  S.  a  nautical  mile  is  1.15157  times  a  common  mile. 


318 


MECHANICAL  REFRIGERATION. 


INCHES  AND  THEIR  EQUIVALENT  DECIMAL  VALUES  IN  PARTS  OF 
A  FOOT. 


Inches. 

Fraction  of  Foot. 

Decimal  Part  of  Foot. 

1 

l1* 

.0833 

2 

.1667 

i 

i 

.25 

4 

i 

.3333 

fi 

5 

.4167 

6 

.5 

7 

.5833 

8 

. 

.6667 

9 

. 

.75 

10 

. 

.8333 

11 

H 

.9167 

12 

V 

1.0 

SQUARE  OR  LAND  MEASURE. 

144  sq.  ins.     =1  sq.  foot. 

9  sq.  ft.      =1  sq.  yard, 
30&  sq.  yds.=  1  sq.  rod. 
40  sq.  rods   =  1  rood. 

4  roods       =  1  acre  =  43560  sq.  ft. 

IH  the  United  States  surveys  a  SECTION  OF  LAND  is  one  mile 
square,  or  640  acres. 

A  square  acre  is  208.71  feet  on  each  side. 
A  circular  acre  is  235.504  feet  in  diameter. 


CUBIC  OR  SOLID  MEASURE. 

1  cubic  foot. 
1  cubic  yard. 


1,728  cubic  inches 
27  cubic  feet 


A  cord  of  wood,  being  4X4X8  feet,  contains  128  cubic  feet.  A 
ton,  2,240  pounds  of  Pennsylvania  anthracite  coal,  in  size  for  do- 
mestic use,  occupies  from  41  to  43  cubic  feet;  bituminous  coal,  44  to 
48  cubic  feet;  coke,  80  cubic  feet. 

LIQUID  MEASURE. 

4  gills       =lpint. 

2  pints     =1  quart. 

4  quarts  =  1  gallon  ==»  231  cubic  inches. 

A  cylinder  31A  inches  in  diameter  and  6  inches  high  will  hold 
almost  exactly  one  quart,  and  one  7  inches  in  diameter  and  6  inches 
high  will  hold  very  nearly  one  gallon. 

This  United  States  gallon  is  only  .8333  of  the  British  imperial 
gallon.  A  cubic  foot  contains  about  71A  United  States  gallons. 

DRY  MEASURE. 

2  pints  =  1  quart. 
8  quarts  =  I  peck. 
4  pecks  —  1  bushel. 

Four  quarts  in  dry  measure  contain  268.8  cubic  inches,  or  .96945 
of  the  British  imperial  gallon.  The  flour  barrel  should  contain 
3.75  cubic  feet  and  196  pounds. 

THE  METRIC  STANDARDS  OF  WEIGHTS  AND  MEASURES. 

The  primary  metric  standards  are :  The  meter,  the  unit  of 
length,  and  the  kilogramme,  the  unit  of  weight,  derived  from  the 
meter,  being  the  two  platinum  standards  deposited  at  the  Palais 
des  Archives  at  Paris.  This  standard  meter  is  alleged  to  be  equal 
to  the  one-ten-millionth  part  of  the  quadrant  of  the  meridian  of 
the  earth.  . 


APPENDIX  I.  319 

METRIC  MEASURES  OF  LENGTH. 

10  millimetres    =  1  centimetre 
10  centimetres   =  1  decimetre 
10  decimetres  | 
100  centimetres  }•=  1  METRE 
1,000  millimetres ) 

10  metres  =  1  decametre 

10  decametres  =  1  hectometre 
10  hectometres  =  1  KILOMETRE 
10  kilometres  =  1  myriametr-e 

A  table  of  METRIC  MEASURES  OF  SURFACE  is  obtained  from  the 
foregoing  table  by  squaring  the  numbers,  and  placing  the  word 
" square  "  before  each  of  the  names;  thus,  100  square  millimetres^ 
1  square  centimetre.  And  A  TABLE  FOR  VOLUMES  is  obtained  by 
cubing  the  numbers,  and  placing  the  word  "cubic"  before  the 
names;  thus,  1,000  cubic  millimetres  =  1  cubic  centimetre. 

FOB  MEASURES  OF  CAPACITY  the  unit  is  the  litre,  and  the  table 
is—  10  centilitres  =  1  decilitre 

10  decilitres    =  1  LITRE 
10  litres  =  1  decalitre 

and  a  litre  contains  1  cubic  decimetre.  This  portion  of  the  capacity 
table  belongs  especially  to  the  measurement  of  liquids. 

FOR  DRY  MEASURES  the  table  is  contained  and  we  have— 

10  litres  =  1  decalitre 

10  decalitres  or          100  litres  =  1  hectolitre 
10  hectolitres  or       1,000  litres  =  1  kilolitre  =  1  cu.  metre. 

METRIC  MEASURES  OF  WEIGHT. 

10  milligrames  =  1  centigramme 

10  centigrammes  =  1  decigramme 

10  decigrammes  =  1  GRAMME 

10  grammes  =  1  decagramme 

10  decagrammes  =  1  hectogramme 
10  hectogrammes 

or  1,000  grammes  =  1  KILOGRAMME 

10  kilogrammes  =  1  myriagramme 
10  myriagrammes 


10  my 
100  kilc 


ogrammes 


10  quintaux 


=  1  quintal  metrigue 
=  1  millier  or  tonne. 


1,000  kilogrammes 
A  millier  or  tonne  is  the  weight  of  1  cubic  metre  of  water  at 
39.1°  F. 

APPROXIMATE  EQUIVALENTS   OF  FRENCH  AND  ENGLISH 
MEASURES. 

1  inch ; 25  millimeters  (exactly  25.4). 

1  yard 11-12  meter. 

1  kilometer %  mile. 

1  mile 1.6  or  1 3-5  kilometers. 

1  square  yard 6-7  square  meter. 

1  acre 4,000  square  meters. 

1  gallon 4V£  liters  fully. 

1  cubic  foot 28.3  liters. 

1  cubic  meter  of  water 1  ton  nearly. 

1  gramme 15l/i  grains  nearly. 

1  kilogramme 2.2  pounds  fully. 

SPECIFIC  GRAVITY  AND  WEIGHT  OF  MATERIALS. 

METALS. 

Specific  Weight  Cu.  ft.  in 
Gravity.  per  cu.  ft.  one  ton- 
Aluminum 2.6  162  13.3 

Antimony,  cast,  6.66  to  6.74 6.7  418  5.3 

Bismuth,  cast  and  native 9.74  607  3.6 

Brass,  copper  and  zinc,  cast  7.8 

to8.4 8.1  504  4.4 

Brass,  rolled 8.4  524  4.2 

Bronze,  copper,  8,  and  tin,  1;  gun 

metal,  8.4  to  8.6 8.5  529  4.2 

Copper,  cast,  8. 6  to  8. 8 8.7  542  4.1 

Copper,  rolled,  8.7  to  8.9 8.8  549  4.0 


320 


MECHANICAL  REFRIGERATION. 


METJ*  LS— CONTINUED. 

Specific  Weight        Cu.  ft.  in 

Gravity,  percu.ft.      one  ton. 

Gold,  cast,  pure  or  24  carat 19 . 258  1204                      1 . 86 

Iron,  cast,  6. 9  to  7.4 7.21  450                        4.8 

"      wrought,  7. B  to  7.9 7.77  485                        4.6 

"     large  rolled  bars 7.69  480                      4.6 

"     sheet  485                      4.6 

Lead 11.4  712                      3.15 

Mercury  at 32°  F 13.62  849                       2.6 

"    60°F 13.58  846                        2.6 

"212°P... 13.38  836                        2.6 

Platinum,  21  to  22 21.5  1,342                       1.6 

Silver 10.5  655                       3.4 

Steel,  crucible,  average 7.842  489                      4.5 

"      cast,              "           7.848  489.3                    4.5 

"      Bessemer 7.852  489.6                   4.5 

Spelter  or  zinc,  6. 8  to  7. 2 7.00  437.5                    5.1 

Tin,  cast,  7. 2  to  7.5 7.35  459.—                  4.8 

Type  metal 10.45  653.—                  3.4 

WOODS. 

Ash,  perfectly  dry 752  47. 1.748 

Ash,  American  white,  dry 61  38                       1.414 

Chestnut,  perfectly  dry 66  41                      1.525 

Elm              •"           "    56  35                        1.302 

Hemlock        "          '•    40  25. .930 

Hickory         "           "    85  53                       1.971 

Maple,  dry 79  49 

Oak,live,dry £5  59  3 

"    wKite.dry 70  44 

"    red 32  to  45 

Pine,  white 40  25                         .930 

Pine,  yellow,  southern 72  45                       1.674 

Sycamore,  perfectly  dry 59  37                      1.370 

Spruce,                               '     40  25                          .930 

STONES  AND  MINERALS. 

Granite,  syenite,  gneiss 2.36to2.96        147. Ito  184.6  12.1 

gray 2.feOto3.06        174.6tol90.8  11.8 

Graphite 2.20  137.2                  16.3 

Gypsum,  plaster  of  Paris 2.2?  141.6                 15.8 

"         in  irregular  lumps 82 

Greenstone,  trap,  2. 8  to  3. 2 3. 187 

Limestones  and  marbles,  2. 4  to 2. 86    2.6  164.4                  13.6 
Limestones  and  marbles,  they  are 

frequently 2.7  168.0                  13.3 

Quicklime,  ground,  loose,  per 

struck  bushel,  62  to  70  Ibs 53                     42 . 2 

Quartz,  common,  finely  pulverized, 

loose 90                     21.8 

Sand,  with   its   natural  moisture 

and  loose .85to.90                 24.8 

Sand,  pure,  quartz,  perfectly  dry..    1.7  106 
Sand,  perfectly  wet,  voids  full  of 

water 118tol29                17.3 

Sandstones,  fit  for  building,  dry, 

2.1to8.73 2.41  150.— 

Standstones,   quarried  and  piled. 

One  measure,  solid,  makes  1% 

piled 86                    26. 

Serpentines 2.81  175.2                  12.8 

Shales,  red  or  black, 2.4  to  2.8 2.6  162 

"      quarried  In  piles 92                     24.3 

Slate,  2.7  to  2.9 2.8  175                      12.8 

Soapstone  or  steatite,  2.65  to  2.8....    2.73  170                     13.1 
Air,  atmosphere  at  60°  F.,  Barom. 

30" 00123  .0765 

Alcohol, pure 793  49.43 

of  commerce 834  52.10 

proof  spirit 916  57.2 

Alabaster,  a   compact  plaster  of 

Paris 3.3J  144.0 


APPENDIX  I. 


321 


STONES  AND  MINERALS— CONTINUED. 

Specific  Weight      Cu.  ft.  in 

Gravity,  per  cu.  ft.  gross  ton. 

Anthracite,  solid,  1.3  to  1.84,  average     1.50  93.5 

Asphaltum  1.4  87.3                   25.6 

Carbonic    acid    gas,  \L/2   times    as 

heavy  as  air 00187 

Charcoal  of  pines  and  oaks 15  to  30                 74.6 

Clay,  potters',  dry,  1.8  to  2.1 1.9  119                    18.8 

Coke,  loose,  of  good  coal 23  to  32 

Cement,  English,  Portland 1.25  to  1.51  78  to  92     23.8  to  28.7 

Cork -....        .25  15.6 

Cork  (comminuted) 6.0 

Earth,  common  loam,  perfectly  dry, 

shaken  moderately  82  to  92 

Earth,  common  loam,  more  moist, 

packed 90  to  100 

Earth,  common  loam,  as  a  soft  flow- 
ing mud 104  to  112 

Fat 93  58 

Glass,  2.5  to  3.45 2.98  186 

Gutta  percha 98  61.1 

Hydrogen  gas  is  14.5  times  lighter 

than   air   and  16  times  lighter 

than  oxygen .00527 

Ice,  at  32°  F 92  67.5                 38.9 

India  rubberj 93  58 

Lard 95  59.3 

Masonry,  of  granite  or  limestones, 

well  dressed... 165                   13.57 

Masonry,    of    brickwork,   pressed 

brick,  fine  joints, 140                    16.— 

Masonry,  of  brickwork,  coarse,  soft 

bricks 100                    22.4 

Mortar,  hardened,  1.4  to  1.9 1.65  103 

Naphtha 848  52.9 

Nitrogen   gas    is    about  1-35  part 

lighter  than  air .0744 

Oils,  whale,  olive 92  57.3 

Oxygen  gas,  a  little  more  than  1-10 

heavier  than  air 00136  .0846 

Petroleum 878  54.8                 40.87 

Pitch 1.15  71.7 

Kosin 1.1  68.6                 32.65 

Salt,  coarse,   per  struck  bushel, 

Syracuse,  N.  Y.,  56  IDS •  45.—               49.77 

Salt,   coarse,  per  struck  bushel, 

St.  Barts,  84  to  90 70.—               32.— 

Salt,   coarse,  per  struck  bushel. 

well  dried,  W.  I.90to96 74 

Sand 90  to  106 

Snow,  fresh  fallen 5  to  12 

"      moistened  and  compacted  by 

rain 15to50 

Sulphur 2  125 

Tallow 94  58.6 

Tar 1.—  62.4 

*Water,  pure  rain,  or  distilled,  at 

32°F.Barom.    30" 62.416 

60°  F.        "           " 1.—  62.366              35.918 

80°  F.       "           "    62.217 

Water,  sea,  1.026  to  1.030 1.028  64.08               34.96 

Wax.  bees 97  60.5 

Gypsum,  plaster  of  Paris.... ,. 2.27  141.6                15.8 

"         in  irregular  lumps 82. 

Gas  (natural) 0.0316 

Limestones  and  marbles,  2. 4  to 2. 86.     2.6  164.4                 13.6 
"           they    are 

frequently 2.7  168.0                 13.3 

Lime-quick,     ground,    loose,    per 

struck  bushel,  62  to  70  pounds..  53.                   42.2 
Quartz,  common,  finely  pulverized, 

loose 90.                  #»,& 


322 


MECHANICAL  BEFRIGERATIOH. 


TABLB  OF  CONTENTS  IN  CUB.  FEET  AND  IN  U.  S.  GALLON, 

(From  Trautwine.) 

Of  231  cubic  inches  (or  7.4805  gallons  to  a  cubic  foot);  and 
for  one  foot  of  length  of  the  cylinder.  For  the  contents 
for  a  greater  diameter  than  any  in  the  table,  take  the 
quantity  opposite  one-half  said  diameter  and  multiply  it 
by  4.  Thus,  the  number  of  cubic  feet  in  one  foot 
length  of  a  pipe  eighty  inches  in  diameter  is  equal  to 
8.728X4=34.912  cub.  ft.  So  also  with  gallons  and  areas. 


Diameter 

in 
Inches. 


£& 
II 

SI 


FOB  1  FOOT 
IN  LENGTH. 


n 

•3  o 


Diameter 

in 
Inches. 


1*3 


FOB  1  FOOT 
IN  LENGTH. 


.0260 
.0313 
.0316 
.0417 
.0469 
.0521 
.0573 
.0626 
.0677 
.0729 
.0781 
.0833 
.1042 
.1250 
.1458 
.1667 
.1875 


.2292 
.2500 
.2708 
.2917 
.3125 
.3333 
.3542 
.3750 
.3958 
.4167 
.4375 
.4583 
.4792 
.5000 
.5208 
.5417 


.0003 
.0005 
.0008 
.0010 
.0014 
.0017 
.0021 
.0026 
.0031 
.0036 
.0042 
.0048 
.0055 
.0085 
.0123 
.0168 
.0218 
.0276 
.0341 
.0413 
.0491 
.0576 
.06H8 
.0767 
.0873 
.0985 
.1105 
.1231 
.1364 
.1503 
.1650 
.1803 
.1963 
.2130 
.2305 


.0040 
.9057 
.0078 
.0102 
.0129 
.9159 
.0193 
.0230 
.0270 
.0312 


.0638 

.0918 

.1250 

.1632 

.2066 

.2550 

.3085 

.3673 

.4310 

.4998 

.5738 

.6528 

.7370 

.8263 

.9205 

.020 

.124 

.234 


594 
724 


10. 


11. 


12. 

13." 
i 

U'i 
15.' 


18. 


.6833 
.6042 
.6250 
.6458 
.6667 
.6875 
.7083 
.7292 
.7500 
.7708 
.7917 
.8125 


.8750 
.8958 
.9167 
.9375 
.9583 
.9792 
IPoot 
1.042 
1.083 
1.125 
1.167 
1.208 
1.250 
1.292 
1.333 
1.375 
1.417 
1.458 
1.500 
1.542 


.2485 
.2673 
.2868 
.3068 
.3275 
.3490 
.3713 
.3940 
.4175 
.4418 
.4668 
.4923 
.6185 
.5455 
.5730 
.6013 
.6303 


.7213 

.7530 

.7864 

.8523 

.9218 

.9940 

.069 

.147 

.227 

.310 

.396 

.485 

.676 

.670 

.767 

.867 


1.859 
1.999 
2.144 

2.295 
2.450 
2.611 
2.777 
2.948 
3.126 
3.306 
3.492 
3.682 
3.879 
4.081 
4.286 
4.498 
4.714 
4.937 
5.163 
5.395 
5.633 
5.876 
6.375 
6.895 
7.435 
7.997 
8.578 
9.180 
9.801 
10.44 
11.11 
11.79 
12.50 
13.22 
13.97 


TABLE  OF  GALLONS. 


Cubic  inch, 
in  a  gallon. 

Weight  of  a 
gallon  in 
pounds 

avoirdupois. 

Gallons  in  a 
cubic  foot. 

Weight  of  a 
cubic  foot  of 
water,     Eng- 
lish standard, 
62.3210286    Ibs. 
avoirdupois. 

United  States. 
New  York.... 
Imperial  

231. 
231.81918 
277.274 

8.33111 
8.00 
10.00 

7.480519 
7.901285 
6.232102 

APPENDIX  I. 


323 


COMPARISON  OF  WEIGHTS   AND  MEASURES. 


METRIC  SYSTEM. 

LENGTH. 

millimeter  =  .0394  inches, 
centimeter  =  .3937  inches. 
METER  «=  39.3708  inches, 

kilometer    =      .6214  miles. 

SQUARE. 

sq.  centimeter  =  .1649  sq.  in. 
sq.  meter  =  10.7631  sq.  ft. 
ARE  .  =  119.5894  sq.  yds. 

hectare  =     2.4711  acres. 

CUBIC. 

CUBIC  METER  =  35.3166  CUblC  ft. 
WEIGHT. 

gram  =     15.4323  grains. 

KILOGRAM    =         2.2046  IbS. 

tonneau       =  2204.55  Ibs. 

DRY  MEASURE. 

centiliter     =    .0181  pints. 
LITER  =    .908  quarts, 

hectoliter    =  2.837  bushels. 

LIQUID  MEASURE. 

centiliter  =      .0211   pints. 
LITER         =    1.0567   quarts, 
hectoliter  =  26.4176  gallons. 


U.  S.  STANDARD. 

LENGTH. 

1  inch   =   2.5309  centimeters. 
1  foot    =  30.4794  centimeters. 
1  yard  =     .9143  meters. 
1  mile   =   1.6093  kilometers. 

SQUARE. 

1  sq.  in.  =  6.4513  sq.  centimeters. 
1  sq.  ft.  =    .0929  sq.  meters. 
1  sq.  yd.  =    .8361  sq.  meters. 
1  acre     =    .4047  hectares. 

CUBIC. 
1  cubic  foot  =  .02831  cubic  meters 

WEIGHT. 

1  Ib.  =  .4536  kilos. 
1  cwt.  =  50.8024  kilos. 
1  ton  =  1016.0483  kilos. 

DRY    MEASURE. 

1  pint       =  55.0661  centiliters. 
1  quart     «=   1.1013  liters. 
1  bushel  =  35.2416  liters. 

LIQUID   MEASURE. 

1  pint      =  47.3171  centiliters. 
1  quart  =     .9563  liters. 
1  gallon  =    3.7854  liters. 


COMPARISON  OF  ALCOHOLOMETERS. 

In  the  absence  of  a  specific  gravity  or  Beaume  scale, 
an  alcoholometer  may  also  be  used  for  ascertaining  the 
strength  of  ammonia  liquor.  The  accompanying  table  is 
to  be  used  in  connection  with  the  table  on  page  97  for 
this  purpose. 


Specific  gravity. 

Per  cent  Tralles 
(by  volume). 

Per  cent  Rich- 
ter  (by  weight). 

Per  cent  Gen- 
dar  United 
States. 

0.793 

100 

100 

100 

0.815 

95 

91.5 

90 

a.  832 

90 

85 

80 

0.848 

85 

79.1 

70 

0.863 

80 

74.2 

60 

0.876 

75 

68.4 

50 

0.889 

70 

62.5 

40 

0.901 

65 

57.3 

30 

0.912 

60 

51.7 

20 

0.923 

55 

46.5 

10 

0.933 

50 

42.0 

P 

0.942 

45 

37.7 

10 

0.951 

40 

33.0 

20 

0.958 

35 

28.7 

30 

0  964 

30 

24.4 

40 

0.970 

25 

20.2 

50 

0.975 

20 

16.4 

60 

0.980 

15 

13.0 

70 

0.985 

10 

10  4 

80 

0.991 

5 

60 

90 

0.999 

0 

1.0 

100 

P  in  the  last  column  stands  for  proof  spirits.  Percentage  over 
proof  U.  S.  gendar  scale  can  be  converted  into  per  cent  Tralles  by 
dividing:  by  two  and  adding  fifty.  Degrees  below  proof  are  con- 
verted by  dividing  by  two  and  subtracting  from  fifty. 


324 


MECHANICAL  REFRIGERATION. 


HORSE  POWER  OF  BELTING. 

TABLE  FOB  SINGLE  LEATHER,  4-PLY  RUBBER  AND  4- PLY  COTTON 

BELTING,  BELTS  NOT  OVERLOADED.    (ONE  INCH  WIDE,  800 

FEET  PER  MINUTE  =  I-HORSE  POWER.) 


Speed  in  Ft. 
Per  Minute. 

WIDTH  OF  BELTS  IN  INCHES. 

2 

3 

4 

5 

6 

8 

10 

12 

14 

16 

18 

20 

h.p 

h.p 

h.p 

h.p 

h.p 

h.p 

h.p 

h.p 

h.p 

h.p 

h.p. 

h.  p. 

400 

1 

14 

2 

24 

3 

4 

5 

6 

7 

8 

9 

10 

600 

I1/* 

2*4 

3 

3% 

44 

6 

74 

9 

104 

12 

134 

15 

800 

24 

3 

4 

5 

6 

8 

10 

12 

14 

16 

18 

20 

1,000 

2 

32* 

5 

6^ 

74 

10 

124 

15 

174 

20 

22!/2 

25 

1,200 

3 

44 

6 

74 

9 

12 

15 

18 

21 

24 

27 

30 

1,500 

3% 

5*4 

7l/2 

94 

114 

15 

18% 

224 

264 

30 

33% 

371/, 

1,800 

VA 

62i 

9 

11* 

134 

18 

22K2 

27 

31l/2 

36 

40l/2 

45 

2,000 

5 

74 

10 

124 

15 

20 

25 

30 

35 

40 

45 

50 

2,400 

6 

9 

12 

15 

18 

24 

30 

36 

42 

48 

64 

60 

2,800 

7 

104 

14 

174 

21 

28 

35 

42 

49 

56 

63 

70 

3,000 

74 

11K 

15 

18% 

22!/2 

30 

374 

45 

624 

60 

674 

75 

3,500 

8% 

13 

174 

22 

26 

35 

44 

524 

61 

70 

79 

88 

4,000 

10 

15 

20 

25 

30 

40 

50 

60 

70 

80 

90 

100 

4,600 

11& 

17 

22l/2 

28 

34 

45 

57 

69 

78 

90 

102 

114 

5,000 

124 

19 

25 

31 

874 

50 

624 

75 

874 

100 

112 

125 

Double  leather,  6-ply  rubber  or  6-ply  cotton  belting 
will  transmit  50  to  75  per  cent  more  power  than  is  shown 
in  this  table. 

A  simple  rule  for  ascertaining  transmitting  power  of 
belting,  without  first  computing  speed  per  minute  that  it 
travels,  is  as  follows:  Multiply  diameter  of  pulley  in 
inches  by  its  number  of  revolutions  per  minute,  and  this 
product  by  width  of  the  belt  in  inches;  divide  this  prod- 
uct by  3,300  for  single  belting,  or  by  2,100  for  double 
belting,  and  the  quotient  will  be  the  amount  of  horse 
power  that  can  be  safely  transmitted. 

HORSE  POWER  OF  SHAFTING. 


Diameter  of  Shaft 


REVOLUTIONS  PER  MINUTE. 


in  Inches. 

100 

125 

150 

175 

200 

h.p. 

h.p. 

h.  p. 

h.  p. 

h.p. 

1516 

1.2 

1.4 

1.7 

2.1 

2.4 

1    3-16 

2.4 

3.1 

3.7 

4.3 

4.9 

1    7-16 

4.3 

5.3 

6.4 

7.4 

8.5 

1  11  16 

6.7 

8.4 

10.1 

11.7 

13.4 

1  15-16 

10.0 

12.5 

15.0 

17.5 

20.0 

2    3-16 

14.3 

17.8 

21.4 

24.9 

28.5 

2    7-16 

19.5 

24.4 

29.3 

34.1 

39.0 

2  11-16 

26.0 

32.5 

39.0 

43.5 

52.0 

2  15-16 

33.8 

42.2 

50.6 

59.1 

67.5 

3    3-16 

43.0 

53.6 

64.4 

75.1 

85.8 

3    7-16 

53.6 

67.0 

79.4 

93.8 

107.2 

3  11-16 

65.9 

82.4 

97.9 

115.4 

121.8 

3  15-16 

80.0 

100.0 

120.0 

140.0 

160.0 

4    7-16 

113.9 

142.4 

170.8 

199.8 

*27.8 

4  15-16 

156.3 

195.3 

234.4 

273.4 

312.5 

APPENDIX   I. 


325 


0  «  00  ^e>  I  W  «  05  •*  O 

'  ° 


61 


O   CO   «D   O 


CO    OS   W    5O 


81 


Mill 


CO    £•<»    L-*    OD 

HIS 


91 


fl 


T-l   CO    CM    O   CO 


81 


CO   OO   CO   O  M» 


Ol    CO   CO   O  !>• 

SliiB 


co  e«  oo  co 

1113 


01 


5O    t-    OS    O 


rs  t-  oo  os  >-i 


'O   CO   O   t-- 


S   3 


O  t-    CO   O  t- 


O  t-  CO  O 


88  SS 


t»  CO    O  t-«  CO 

S  SS  3  88  85 


CO    t«  00   05    O 


326 


MECHANICAL  REFRIGERATION. 


TABLE  FOB   CONVERTING   FEET    HEAD    OF  WATER  INTO 
PRESSURE  PER  SQUARE  INCH. 


Feet. 
Head. 

Pounds  per 
square  inch. 

Feet. 
Head. 

Pounds  per 
square  inch. 

Feet. 
Head. 

Pounds  per 
square  inch. 

1 

.43 

55 

23.82 

190 

82.29 

2 

.87 

60 

25.99 

200 

86.62 

3 

1.30 

65 

2&15 

225 

97.45 

4 

1.73 

70 

30.32 

250 

108.27 

5 

2.17 

75 

32.48 

275 

119.10 

6 

2.60 

80 

34.65 

300 

129.93 

7 

8.03 

85 

36.81 

325 

140.75 

8 

3.40 

90 

38.98 

350 

151.58 

9 

3.90 

95 

41.14 

375 

162.41 

10 

4.33 

100 

43.31 

400 

173.24 

15 

6.50 

110 

47.64 

500 

216.55 

20 

8.66 

120 

51.97 

600 

259.85 

25 

10.83 

130 

56.30- 

700 

303.16 

30 

12.99 

140 

60.63 

800 

346.47 

35 

15.16 

150 

64.96 

900 

389.78 

40 

17.32 

160 

69.29 

1000 

433.09 

46 

19.49 

170 

73.63 

60 

21.65 

180 

77.96 

.....V 

1 

14.7 
14.7 
0.4X 

lb.  pressure 
lb.         - 
Ibs.  or  1  atmosphere, 

i£ 

Iper  square  inch 
is  equivalent  to 
a  head  of  water 
of... 

2.3093  feet. 
27.71  inches, 
33.947  feet. 
10.347  meters. 
1  foot. 

43.3 

Ibs. 

J 

100  feet. 

TABLE   OP   THEORETICAL    HORSE   POWER    REQUIRED  TO 
RAISE  WATER  TO  DIFFERENT    HEIGHTS. 


Feet. 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

60 

Gals,  per 

Minute. 

5 

.006 

.012 

.019 

.025 

.031 

.037 

.044 

.05 

.06 

.06 

.07 

JO 

.012 

.025 

.037 

.050 

.062 

.075 

.087 

.10 

.11 

.12 

.15 

15 

.019 

.037 

.056 

.075 

.094 

.112 

.131 

.15 

.17 

.19 

.22 

20 

.025 

.050 

.075 

.100 

.125 

.150 

.175 

.20 

.22 

.25 

.30 

25 

.031 

.062 

.093 

.125 

.156 

.187 

.219 

.25 

.28 

.31 

.37 

30 

.037 

.075 

.112 

.150 

.187 

.225 

.262 

.30 

.34 

.37 

.45 

35 

.043 

.087 

.131 

.175 

.219 

.262 

.306 

.35 

.39 

.44 

.52 

40 

.050 

.100 

.150 

.200 

.250 

.300 

.350 

.40 

.45 

.50 

.60 

45 

.056 

.112 

.168 

.225 

.281 

.337 

.394 

.45 

.51 

.56 

.67 

50 

.062 

.125 

.187 

.250 

.312 

.375 

.437 

.50 

.56 

.62 

.75 

60 

.075 

.150 

.225 

.300 

.375 

.450 

.525 

.60 

.67 

.75 

.90 

75 

.093 

.187 

.281 

.375 

.469 

.562 

.656 

.75 

.84 

.94 

1.12 

90 

.112 

.225 

.337 

.450 

.562 

.675 

.787 

.90 

1.01 

1.12 

1.35 

100 

.125 

.250 

.375 

.500 

.625 

.750 

.875 

1.001.12 

1.25 

1.50 

125 

.156 

.312 

.469 

.625 

.781 

.937- 

1.094 

1.251.41 

1.56 

1.87 

150 

.187 

.375 

.562 

.750 

.937 

1.125 

1.312 

1.501.69 

1.87 

2.25 

175 

.219 

.437 

.656 

.875 

1.093 

1.312 

1.531 

1  75  1.97 

2.19 

2.63 

200 

.250 

.500 

.750 

1.000 

1.250 

1.500 

1.750 

2:00|2.25 

2.50 

3.00 

250 

.312 

.625 

.937 

1.250 

1.562 

1.875 

2.187 

2  5012.81 

3.12 

3.75 

300 

.375 

.750 

1.125 

1.500 

1.875 

2.250 

2.625 

d.  003.  37 

3.75 

4.50 

350 

.437 

.875 

1.312 

1.750 

2.187 

2.625 

3.062 

o  Js.94 

4.37 

5.25 

400 

.500 

1.000 

1.500 

2.000 

3.500 

3.000 

3.500 

lS3460 

5.00 

6.00 

500 

.625 

1.250 

1.875 

2.500 

a.  125 

3.750 

4.375 

I.-88I8-" 

6.25 

7.50 

APPENDIX  I. 


327 


jad 


•spuno -i  uj 

M       RHOrTTIOnmJJ         ;     ;     ;     '     '     ;     ;     ;     *    *    •<=>     ;  O      OOOOOOO<M« 
*pUO09g  jad 

me^coeo^tatnoo 

•spunod  m  i  :  •  :  i  i§  jS'jfc  -8I888BS58  : 

r,    ~sor  uoiaoti a  \  ::<=>:<=>  :®    -Hp-cjw^tot- 

g 

"  "  ^    ^    ^    ^    ^~^    ^    ^55    HO    TCO     i— i  o  '*o  M< 

puooggjad       :::::::: •  :«  :«  :»   r««^M.«* 

C4     ;CO       USWt-QOOrHN 

I      .    .    .     .0    •     •     •     •U5'* 

•spunoj 

.— .         G1 

o 

M    -puooagaad    I  ::  ::":::  ;«^SS33j§««o<»<N,*t^ 

o    sso'r  uorjotjjj  I    '  I  '.  I®  ;  I  I  •O'Hce^t-osN 
fc;   J 

•puooag  jad 

8didurooi9A|        :  :rt  :     :  ico^ooorHfo 

•spunoj  ui 

„        S! 

6 

•puooag  jad         :®  ;<=>  i®  :®  I'"?®'^00.00.^** 

•1H    ;C4     'CO     ;•*     'U3t-OMU5^0 

M       -spunoj  ut 

O      SSO'T   UOl^OW^  I  OOOTHWCOIO^OOOO 
fe  '  _ 

•puoo9g  aad 

O  iH  N  CO  •*  »O  «D  t- 00  O>  CO  03 

(j?      -sputio  j  n|     I 
o 

•puooagjad     I 

8dlJUl'OOT8A   I  »HC<CO>OCOt*0>QT7|COg> 

.      -spunoj  ui 
w    BSOT; 

^H  ^^— — 

•puooagaad     I  °R"^1c<!eo.ce.f0. 

9dl£  UI  'OO19A  I  W-*»C»o«Mj50 

•spuno^  nt       «ot-«*o 
g    ssoi 
M 

•pnooag  aad 

9dii  ui  -ooia 

•spuno  jui       «°° 
ssoi 

•puooagaad      ^°?  :     :  •  :  :  ;  :  : 

000 


jod 


328  MECHANICAL  REFRIGERATION. 

FLOW  OF  STEAM  THROUGH  PIPES. 


23 

Diameter  of  Pipe  in  inches.    Length  of  each  Pipe, 

z  a 

240  Diameters. 

0)  02 

£| 

* 

1 

1*6 

2 

f* 

3 

4 

1! 

a  ® 

1-4   ft 

Weight  of  Steam  per  Minute  in  Pounds,  with  One  Pound 
Fall  of  Pressure. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

1 

1.16 

2.07 

5.7 

10.27 

15.45 

25.38 

46.86 

10 

1.44 

2.57 

7.1 

12.72 

19.15 

31.45 

48.05 

20 

1.70 

3.02 

8.3 

14.94 

22.49 

36.94 

68.20 

30 

1.91 

3.40 

9.4 

16.84 

25.35 

41.63 

76.84 

40 

2.10 

3.74 

10.3 

18.51 

27.87 

45.77 

84.49 

50 

2.27 

4.04 

11.2 

20.01 

30.13 

49.48 

91.34 

60 

2.48 

4.32 

11.9 

21.38 

32.19 

52.87 

97.60 

70 

2.57 

4.58 

12.6 

22.65 

34.10 

56.00 

103.37 

80 

2.71 

4.82 

13.3 

23.82 

35.87 

58.91 

108.74 

90 

2.83 

5.04 

13.9 

24.92 

37.52 

61.62 

113.74 

100 

2.95 

5.25 

14.5 

25.96 

39.07 

64.18 

118.47 

130 

3.16 

5.63 

15.5 

27.85 

41.93 

68.87 

127.12 

150 

3.45 

6.14 

17.0 

30.37 

45.72 

75.09 

138.61 

For  any  other  given  length  of  pipe  divide  240  by  the 
given  length  in  diameters  and  multiply  the  tubular 
values  by  the  square  root  of  the  quotient,  to  give  the 
flow  for  one  pound  fall  of  pressure. 

For  any  other  given  fall  of  pressure  multiply  the 
tubular  weight  by  the  square  root  of  the  given  fall  of 
pressure. 

HORSE  POWER  OF  BOILERS. 

Thirty  pounds  of  water  evaporated  at  seventy  pounds 
steam  pressure  per  hour  from  feed  water  at  100°=1  horse 
power.  In  calculating  horse  power  of  steam  boilers 
consider  for— 

Tubular  boilers,  fifteen  square  feet  of  heating  surface 
equivalent  to  one  horse  power. 

Flue  boilers,  twelve  square  feet  of  heating  surface 
=1  horse  power. 

Cylinder  boilers,  ten  square  feet  of  heating  surface 
=1  horse  power. 

Doubling  the  diameter  of  a  pipe  increases  its  capac- 
ity four  times;  friction  of  liquids  increases  as  the  square 
of  velocity. 

To  find  the  pressure,  in  square  inches,  of  a  column  of 
water:  Multiply  the  height  of  the  column  in  feet  by  .434 
approximately.  Every  foot  elevation  is  equal  to  half  pound 
pressure  per  square  inch;  this  allows  for  ordinary  friction. 


APPENDIX  I. 


329 


WOOD'S  TABLE  OF  SATURATED  AMMONIA.* 
Recalculated  by  GEORGE  DAVIDSON,  M.  E. 


Tempera- 
ture. 

Pressure, 
Absolute. 

& 

** 

y 

2s 

I!* 

P» 

ig 

W   (4 

§1 

^    -?s 

•2*  •»  * 

c3 

-«* 

§5 

h 

6 

jju 

N 

|| 

s!^ 

o  5"S 

"o^  § 

Sl| 

O  3*^ 

tL 

en 

-P 

O 

ai  3 

'C 

*H     **  rr> 

a>(v  « 

®  <•%  ® 

43  O  £} 

+3  0  o 

QQ 

Q) 

rHtl 

3 

•3*3 

fP       fl       f4 

O    G  4-j 

S   fc 

f]        F^l 

JPMS 

£^2 

^ 

£H  **"* 

15" 

a  . 

a  ^ 

to  ^  o 

+3  O*£* 

^  a>£ 

§£« 

*  •§ 

3f      3 

S 

bo 

A- 

1 

£ 

|A 

O 

|SP 

"3  P.P 

"^  fl 

p 

—40 

420.66 

1539.90 

10.69 

—4.01 

579.67 

24.388 

.02348 

.0410 

42.589 

—40 

39 

1 

1584.43 

11.00 

—3.70 

579.07 

23.735 

.02351 

.0421 

42.535 

39 

38 

2 

1630.03 

11.32 

—3.38 

578.42 

23.102 

.02354 

.0433 

42.483 

38 

37 

3 

1676.71 

11.64 

—3.06 

577.88 

22.488 

.02357 

.0444 

42.427 

37 

36 

4 

1724.51 

11.98 

—2.72 

577.27 

21.895 

.02359 

.0457 

42.391 

36 

—35 

425.66 

1773.43 

12.31 

-2.39 

576.68 

21.321 

.02362 

.0469 

42.337 

—35 

34 

6 

1823.50 

12.66 

—2.04 

576.08 

20.763 

.02364 

.0482 

42.301 

34 

33 

7 

1874.73 

13.02 

—1.68 

575.48 

20.221 

.02366 

.0495 

42.265 

33 

32 

8 

1927.17 

13.38 

—1.32 

574.89 

19.708 

.02368 

.0507 

42.213 

32 

31 

9 

1980.78 

13.75 

—0.95 

574.39 

19.204 

.02371 

.0521 

42.176 

31 

—30 

430.66 

2035.69 

14.13 

—0.57 

573.69 

18.693 

.02374 

.0535 

42.123 

—30 

29 

1 

2091.83 

14.53 

—0.17 

573.08 

18.225 

.02378 

.0549 

42.  052 

29 

28 

2 

2149.23 

14.92 

+0.22 

572.48 

17.759 

.02381 

.0563 

42.000 

28 

27 

3 

2207.94 

15.33 

+0.63 

571.89 

17.307 

.02384 

.0577 

41.946 

27 

26 

4 

2267.97 

15.76 

+1.05 

571.28 

16.869 

.02387 

.0693 

41.893 

26 

—25 

435.66 

2329.34 

16.17 

+1.47 

570.68 

16.446 

.02389 

.0608 

41.858 

-25 

24 

6 

2392.09 

16.61 

1.91 

570.08 

16.034 

.02392 

.0624 

41.806 

24 

23 

7 

2456.23 

17.05 

2.35 

569.48 

15.633 

.02395 

.0640 

41.754 

23 

22 

8 

2520.45 

17.50 

2.8 

568.88 

15.252 

.02398 

.0656 

41.701 

22 

21 

9 

2588.77 

17.97 

3.27 

568.27 

14.876 

.02401 

.0672 

41.649 

21 

—20 

440.66 

2657.23 

18.45 

+3.75 

567.67 

14.507 

.02403 

.0689 

41.615 

-20 

19 

1 

2727.17 

18.94 

^.24 

567.06 

14.153 

.02406 

.0706 

41.563 

19 

18 

2 

2798.62 

19.43 

4.73 

566.43 

13.807 

.02409 

.0725 

41.511 

18 

17 

3 

2871.61 

19.94 

5.24 

565.85 

13.475 

.02411 

.0742 

41.480 

17 

16 

4 

2946.17 

20.46 

5.76 

565.25 

13.150 

.02414 

.0760 

41.425 

16 

—15 

445.66 

3022.31 

20.99 

+6.29 

564.64 

12.834 

.02417 

.0779 

41.374 

-15 

14 

6 

3100.07 

21.53 

6.83 

564.04 

12.527 

.02420 

.0798 

41.322 

14 

13 

7 

3179.45 

22.08 

7.38 

563.43 

12.230 

.02423 

.0818 

41.271 

13 

12 

8 

3260.52 

22.64 

7.94 

562.82 

11.939 

.02425 

.0838 

41.237 

12 

11 

9 

3343.29 

23.22 

8.52 

562.21 

11.659 

.02428 

.0858 

41.186 

11 

—10 

450.66 

3427.75 

23.80 

+9.10 

561.61 

11.385 

.02431 

.0878 

41.135 

—10 

9 

1 

3513.97 

24.40 

9.70 

560.99 

11.117 

.02434 

.0899 

41.084 

9 

8 

2 

3601.97 

25.01 

10.31 

560.39 

10.860 

.02437 

.0921 

41.034 

8 

7 

3 

3691.75 

25.64 

10.94 

559.78 

10.604 

.02439 

.0943 

41.000 

7 

6 

4 

3783.37 

26.27 

11.57 

559.17 

10.362 

.02442 

.0965 

40.950 

6 

—5 

455.66 

3876.85 

26.92 

+12.22 

558.56 

10.125 

.02445 

.0988 

40.900 

—5 

4 

6 

3972.62 

27.59 

12.89 

557.94 

9.894 

.02448 

.1011 

40.845 

4 

3 

7 

4069.48 

28.26 

13.56 

557.33 

9.669 

.02451 

.1034 

40.799 

3 

2 

8 

4168.70 

28.95 

14.25 

556.73 

9.449 

02454 

.1058 

40.749 

2 

1 

9 

4269.90 

29.65 

14.95 

556.11 

9.234 

.02457 

.1083 

40.700 

1 

+0 

460.66 

4373.10 

30.37 

+15.67 

555.50 

9.028 

.02461 

.1107 

40.650 

+0 

1 

1 

4478.32 

31.10 

16.40 

554.88 

8.825 

.02463 

.1133 

40.601 

1 

2 

2 

4486.60 

31.84 

17.14 

554.27 

8.630 

.02466 

.1159 

40.551 

2 

a 

3 

4694.96 

32.60 

17.90 

553.65 

8.436 

.02469 

.1186 

40.502 

3 

4 

4 

4806.46 

33.38 

18.68 

553.04 

8.250 

.02472 

.  1212 

40.453 

4 

*  For  values  at  temperatures  higher  than  100°  F.  see  Wood's  table 
on  page  92. 


330  MECHANICAL  REFRIGERATION. 

WOOD'S  TABLE  OF  SATURATED  AMMONIA— Continued. 


Tempera- 
ture. 

Pressure, 
Absolute. 

Si 

!! 

£- 

!=>_ 

P* 

flff 

|| 

ri 

i 

II 

*J 

K 

I^U 

!|l 

O   Q   0} 

IS  O 

<%  a  o 

Ogfe 

7j    ^  ^ 

~ 

sH 

3^" 

13 

t3 

§,§•£ 

-po^ 

In* 

IK^O 

WJ^ 

•fi^lS 

S 

0 

g 

noaftn 

OQQ  ft 

esPMM 

8SP 

"o  a2 

13  p-2 

'55  .So 

'®.So 

te 

Q 

<J 

PH 

C5 

4 

> 

^ 

> 

Q 

~+5 

466.66 

4920.11 

34.16 

+19.46 

552.43 

8.070 

.02475 

.1240 

40.404 

+5 

6 

6 

5035.95 

34.97 

20.27 

551.81 

7.892 

.02478 

.1267 

40.355 

6 

7 

7 

5153.99 

35.79 

21.09 

551.19 

7.717 

.02480 

.1296 

40.322 

7 

8 

8 

5274.28 

36.63 

21.93 

550.58 

7.553 

.02483 

.1324 

40.274 

8 

9 

9 

6396.83 

37.48 

22.78 

549.96 

7.388 

.02486 

.1353 

40.225 

9 

+10 

470.66 

5521.71 

38.34 

+23.64 

549.35 

7.229 

.02490 

.1383 

40.160 

+10 

11 

1 

6649.48 

39.23 

24.53 

548.73 

7.075 

.02493 

.1413 

40.112 

11 

12 

2 

5778.50 

40.13 

25.43 

548.11 

6.924 

.02496 

.1444 

40.064 

12 

13 

3 

5910.52 

41.04 

26.34 

547.49 

6.786 

.02499 

.1474 

40.016 

13 

14 

4 

6044.96 

41.98 

27.28 

546.88 

6.632 

.02502 

.1507 

39.968 

14 

+15 

475.66 

6182.00 

42.94 

+28.24 

546.26 

6.491 

.02505 

.1541 

39.920 

+15 

16 

6 

6321.24 

43  90 

29.20 

545.63 

6.355 

.02508 

.1573 

39.872 

16 

17 

7 

6463.24 

44.88 

30.18 

545.01 

6.222 

.02511 

.1607 

39.872 

17 

18 

8 

6607.77 

45.89 

31.19 

544.39 

6.093 

.02514 

.1641 

39.777 

18 

19 

9 

6754.90 

46.91 

32.21 

543.74 

5.966 

.02517 

.1676 

39.729 

19 

+20 

480.66 

6904.68 

47.95 

33.25 

543.15 

5.843 

.02520 

.1711 

39.682 

+20 

21 

1 

7057.15 

49.01 

34.31 

642.53 

5.722 

.02523 

.1748 

39.635 

21 

22 

2 

7211.33 

50.09 

35.39 

541.90 

5.605 

.02527 

.1784 

39.572 

22 

23 

3 

7370.27 

51.18 

36.48 

641.28 

5.488 

.0^529 

.1822 

39.541 

23 

24 

4 

7530.96 

52.30 

37.60 

540.66 

5.378 

.02533 

.1860 

39.479 

24 

+25 

485.66 

7694.52 

53.43 

+38.73 

540.03 

5.270 

.02536 

.1897 

39.432 

+25 

26 

6 

7860.89 

54.59 

39.89 

539.41 

5.163 

.02539 

.1937 

39.386 

26 

27 
28 

7 
8 

8030.16 

8202.38 

55.76 
66.96 

41.06 
42.26 

538.78 
538.16 

5.058 
4.960 

.02542 
.02545 

.1977 
.2016 

39.339 
39.292 

27 
28 

29 

9 

8377.56 

58.17 

43.47 

537.53 

4.858 

.02548 

.2059 

39.246 

29 

+30 

490.66 

8555.74 

59.42 

+44.72 

536.91 

4.763 

.02551 

.2099 

39.200 

+30 

31 

1 

8736.96 

60.67 

45.97 

536.28 

4.668 

.02554 

.2142 

39.115 

31 

32 

2 

8921.26 

61.95 

47.25 

535.66 

4.577 

.02557 

.2185 

39.108 

32 

33 

3 

9108.71 

63.25 

48.55 

535.03 

4.486 

.02561 

.2229 

39.047 

33 

34 

4 

9299.32 

64.58 

49.88 

534.40 

4.400 

.02564 

.2273 

39.001 

34 

+35 

495.66 

9493.07 

65.92 

+51.22 

533.78 

4.314 

.02568 

.2318 

38.940 

+35 

36 

6 

9690.04 

67.29 

52.59533.13 

4.234 

.  02571 

.236238.894 

36 

37 

7 

9890.  75 

68.68 

53.98532.52 

4.157 

.02574 

.241338.850 

37 

38 

8 

10093.91 

70.09 

55.  39J531.89 

4.068 

.02578 

.245838.789 

38 

39 

9 

10300.88 

71.53 

56.83 

531.26 

3.989 

.02582 

.2507 

38.729 

39 

+40 

600.66 

10511.16 

72.99 

+58.29 

530.63 

3.915 

.02585 

.2554 

38.684 

+40 

41 

1 

10724.95 

74.48 

59.78529.99 

3.839 

.02588 

.260538.639 

41 

42 

2 

10942.18 

75.99 

61.29529.36 

3.766 

.02591 

.265538.595 

42 

43 

3 

11162.93 

77.52 

62.82528.73 

3.695 

.02594 

.2706  '38.  550 

43 

44 

4 

11387.21 

79.08 

64.38 

528.10 

3.627 

.02597 

.2757 

38.499 

44 

+45 

505.66 

11615.12 

80.66 

+65.96 

527.47 

3.  "559 

.02600 

.2809 

38.461 

+45 

46 

6 

11846.64 

82.27 

67.57 

526.83 

3.493 

.02603 

.2863 

38.417 

46 

47 

7 

12081.80 

83.90 

69.20 

526.20 

3.428 

.02606 

.2917 

38.373 

47 

48 

8 

12320.71 

85.56 

70.86 

525.57 

3.362 

.02609 

.2974 

38.328 

48 

49 

9 

12563.36 

87.25 

72.55 

524.93 

3.303 

.02612 

.3027 

38.284 

49 

+50 

510.66 

12809.91 

88.96 

+74.26 

524.30 

3.242 

.02616 

.3084 

38.226 

-1-50 

51 

1 

13080.21 

90.70 

76.00523.66 

3.182 

.02620 

.3143 

38.167 

51 

52 

2 

13314.43 

92.46 

77.76523.03 

3.124 

.02623 

.3201 

88.124 

52 

63 

3 

13572.52 

94.25 

79.55  522.39 

3.069 

.02626 

.3258 

38.080 

53 

54 

4 

13834.64 

96.07 

81.  371521.  76 

3.012 

.02629 

.3320 

38.037 

54 

APPENDIX  I.  331 

WOOD'S  TABLE  OF  SATURATED  AMMONIA— Continued. 


Tempera- 
ture. 

Pressure, 
Absolute. 

i$ 

*i 

•§i 

8=» 

8°* 

5  a 

!*' 

2  S3  " 

emper-|| 
iture.  j| 

. 

SM 

h  . 

eSt 

5£,4 

fel  • 

^a 

cw  'Ho 

^"1? 

H 

w 

S« 

1 

1 

p,g 

si- 

*i$ 

|*I 

J*| 

43  0  0 

fl^2 

•pO  o 

•S*s 

tn 

1- 

1 

fjffii 

ao-^ 

ill 

®£& 

lls 

"o  P.3 

Sfg  a 

SlsS 

Sj 

£ 

cu 

o 

H 

* 

> 

J 

5j 

Q 

+55 

515.66 

14100.74 

97.92 

+83.22 

521  12 

2.958 

.02632 

.3380 

37.994 

+55 

66 

6 

14370.92 

99.80 

85.10 

520.48 

2.905 

.02636 

.3442 

37.936 

56 

57 

7 

14645.18 

101.70 

87.00 

519.84 

2.853 

.02639 

.3505 

37.893 

57 

58 

8 

14923.98 

103.64 

88.94 

519.20 

2.802 

.02643 

.3568 

37.835 

58 

59 

9 

15206.28 

105.60 

90.90 

618.57 

2.753 

.02646 

.3632 

37.793 

59 

+60 

520.66 

15493.09 

107.59 

+92.89 

517.93 

2.705 

.02651 

.3697 

37.736 

+60 

61 

1 

15784.23 

109.61 

94.91 

517.29 

2.658 

.02654 

.3762 

37.678 

61 

62 

2 

16079.67 

111.66 

96.96 

516.65 

2.610 

.02658 

.3831 

37.622 

62 

63 

3 

16379.51 

113.75 

99.05 

516.01 

2.565 

.02661 

.3898 

37.579 

63 

64 

4 

16683.75 

115.86 

101.16 

515.37 

2.520 

.02665 

.3968 

37.523 

64 

+65 
66 

525.66 
6 

16992.50 
17305.70 

118.09 

120.18 

+103.33 

105.48 

514.73 

514.09 

2.476 
2.433 

.02668 
.02671 

.4039 
.4110 

37.481 
37.439 

+65 
66 

67 

7 

17623.45 

122.38 

107.68 

513.45 

2.389 

.02675 

.4189 

37.383 

67 

68 

8 

17945.89 

124.62 

109.92 

512.81 

2.351 

.02678 

.4254 

37.341 

68 

69 

9 

18272.81 

126.89 

112.19 

512.16 

3.310 

.02682 

.4329 

37.285 

69 

+71 

530.66 
1 

18604.53 
18941.00 

129.19 
131.54 

+114.49 
116.84 

511.52 
510.87 

2.272 
2.233 

.02686 
.02689 

.4401 
.4479 

37.230 

37.188 

+70 
71 

72 

2 

19282.21 

133.90 

119.20 

510.22 

2.194 

.02693 

.4558 

37.133 

72 

73 

3 

19628.32 

136.31 

121.61 

509.58 

2.153 

.02697 

.4645 

37.079 

73 

74 

4 

19979.22 

138.74 

124.04 

508.93 

2.122 

.02700 

.4712 

37.037 

74 

+75 

535.66 

20335.16 

141.22 

+126.52 

508.29 

2.087 

.02703 

.4791 

36.995 

+75 

6 

20696.00 

143.  72 

129.02 

507.64 

2.052 

.02706 

.4873|36.954 

76 

77 

7 

21061.85 

146.26 

131.56 

506.99 

2.017 

.02710 

.4957  36.900 

77 

78 

8 

21432.82 

148.84 

134.14 

506.34 

1.995 

.02714 

.501236.845 

78 

79 

9 

21808.85 

151.45 

136.75 

505.69 

1.952 

.02717 

.512336.805 

79 

+80 

540.66 

22190.15 

154.10 

+139.40 

505.05 

1.921 

.02721 

.520536.751 

+80 

81 

1 

22576.51 

156.78 

142.08 

504.40 

1.889 

.02725 

.529436.696 

81 

82 

2 

22968.88 

159.50 

144.80 

503.75 

1.858 

.02728 

.538236.657 

82 

83 

3 

23365.38 

162.26 

147.56 

603.10 

1.827 

.02732 

.547336.603 

83 

84 

4 

23767.81 

166.05 

150.35 

502.45 

1.799 

.02736 

.5558 

36.549 

84 

+85 

545.66 

24175.61 

167.88 

+153.18 

501.81 

1.770 

.02739 

.5649 

36.509 

+85 

8b 

6 

24588.92 

170.75 

156.05 

501.15 

1.741 

.02743 

.574436.456 

86 

87 

7 

25007.80 

173.66 

158.96 

500.50 

1.714 

.02747 

.583436.407 

87 

88 

8 

25432.16 

176.61 

161.91 

499.85 

1.687 

.02751 

.592736.350 

88 

89 

9 

25862.14 

179.59 

164.89 

499.20 

1.660 

.02754 

.6024 

36.311 

89 

*1 

550.66 
1 

26297.88 
26739.88 

182.62 
185.69 

+167.92 
170.99 

498.55 
497.89 

1.634 

1.608 

.02758 
.02761 

.6120 
.6219 

36.258 
36.219 

+90 
91 

92 

2 

27186.56 

188.79 

174.09 

497.24 

1.583 

.02765 

.6317 

36.166 

92 

93 

3 

27639.43 

191.94 

177.24 

496.59 

1.558 

.02769 

.6418 

36.114 

93 

94 

4 

28098.26 

195.13 

180.43 

495.94 

1.534 

.02772 

.6518 

36.075 

94 

+95 

555.66 

28563.00 

198.35 

+183.65 

495.29 

1.510 

.02776 

.6622 

36.023 

+95 

96 

6 

29033.86 

201.62 

186.92 

494.63 

1.486 

.02780 

.6729 

35.971 

96 

97 

7 

29510.69 

204.94 

190.24 

493.97 

1.463 

.02784 

.6835 

35.919 

97 

.98 

8 

29993.52 

208.29 

193.59493.32 

1.442 

.02787 

.6934 

35.8K1 

98 

99 

9 

30482.52 

211.68 

196.98 

492.66 

1.419 

.02791 

.7047 

35.829 

99 

+100 

560.66 

30977.78 

215.12 

+200.42 

492.01 

1.398 

.02795 

.7153 

35.778 

+100 

332 


MECHANICAL  REFRIGERATION. 
TABLE  OF  HUMIDITY  IN  AIR. 


2 

g         ri 

0>  p 

2 

g         ^ 

<H§£ 

2 

En^-cS^ 

CQ-gja  . 

5 

^^•2- 

OQ-g.2    • 

i| 

iSsa 

jS  O  p,"-* 

t*  ^^<J  ^ 

£4 

c  o> 

PO 

!|8| 

1^5*1 

g"w^S 

"S  py^^o 

a 

c'"^^ 

|£  8.?^O 

5 

>° 

H 

0 

ffo 

—10 

2.1 

2.3 

+13 

11.2 

11  4 

—  9 

2.3 

2.5 

+14 

11.9 

12.1 

—  8 

2.5 

2.7 

+15 

12.7 

12.9 

—  7 

2.7 

2.9 

+16 

13.5 

13.6 

—  6 

2.9 

3.2 

+17 

14.4 

14.6 

—  6 

3.1 

3.4 

+18 

15.4 

15.4 

—  4 

3.4 

3.7 

+19 

16.3 

16.3 

—  3 

3.7 

4.0 

+20 

17.4 

17.3 

—  2 

4.0 

4.3 

+21 

18.5 

18.4 

—  1 

4.3 

4.6 

+22 

19.7 

19.4 

0 

4.6 

4.9 

--23 

20.9 

20.6 

+  1 

6.0 

5.3 

--24 

22.2 

21.8 

+  2 

5.3 

5.6 

--25 

23.6 

23.1 

+  3 

5.7 

6.0 

--26 

25.0 

24.4 

T  4 

6.1 

6.4 

+27 

26.6 

25.8 

T  5 

6.5 

6.8 

+28 

28.1 

27.2 

T  6 

7.0 

7.3 

+29 

29.8 

28.8 

*4~  7 

7.5 

7.8 

+30 

31.5 

30.4 

+  8 

8.0 

8.3 

+31 

33.4 

32.1 

+  9 

8.6 

8.9 

+32 

35.4 

33.8 

+10 

9.2 

9.4 

+33 

37.4 

35.7 

+11 

9.8 

10.1 

+34 

39.3 

37.6 

+12 

10.5 

10.7 

+35 

41.5 

39.3 

TABLE  SHOWING  AMOUNT  OF  MOISTURE  TO  100  LBS.   OF 

DRY  AIR  WHEN   SATURATED  AT  DIFFERENT 

TEMPERATURES. 


Temper- 
ature. 
Fahr. 
Degrees. 

Weight 
of  Vapor 

in  Ibs. 

Temper- 
ature. 
Fahr. 
Degrees. 

Weight 
of  Vapor 
in  Ibs. 

Temper- 
ature. 
Fahr. 
Degrees. 

Weight 
of  Vapor 
in  Ibs. 

—20 
—10 
0 
+10 
20 
32 
42 
52 

0.0350 
0.0574 
0.0918 
0.1418 
0.2265 
0.379 
0.561 
0.819 

62 
72 
89 
92 
102 
112 
122 
132 

1.179 
1.680 
2.361 
3.289 
4.547 
6.253 
8.584 
11.771 

142 
152 
162 
172 
182 
192 
202 
212 

16.170 
22.465 
31.713 
46.338 
71.300 
122.  (543 
280.230 
Infinite. 

LATENT  UNITS  OI 
TION  I 

"  HEAT  OF  FUSION    AND    VOLATILIZA- 
ER  POUND  OF  SUBSTANCE. 

Solids  Melted 
to  Liquids.      -f, 

Latent 
Heat 
B.  T.  Units 

Liquids  Converted 
to  Vapor. 

Latent 
Heat 
B.  T.  Units 

Ice  to  water  .... 

142 

25.6 
50.6 
17.0 
9.72 
5.00 
175 
550 
233 
46.4 

Water  to  steam  
Ammonia  

966 
495 
372 
298 
212 
174 
137 
184 
167 
175 

Tin  

Zinc  

Alcohol,  pure  

Carbonic  acid  
Bisulphite  of  carbon. 
Ether,  sulphuric  
Essence  of  turpentine 
Oil  of  turpentine  
Mercury 

Lead 

Mercury 

Beeswax      ......  .... 

Bismuth 

Cast  iron 

Spermaceti  

Chimogene  

APPENDIX  I. 


333 


COLD  STORAGE  RATES. 

The  charges  for  cold  storage  and  rates  for  freezing 
must  depend  greatly  upon  various  conditions,  such  as 
capacity  of  house,  demand  and  supply,  competition  to  be 
met  and  other  local  conditions.  For  general  use  and  as 
a  basis  for  figuring,  the  following  rates,  which  are  those 
now  in  force  in  the  principal  cold  storage  points  and  which 
are  generally  adhered  to,  will  be  found  useful: 

COLD  STORAGE  BATES  PER  MONTH. 


GOODS  AND  QUANTITY. 

11 

El 

Each 
Succeeding 
Month. 

In  Large 
Quantities, 
per  Month. 

Season  Rate 
per  Bbl. 
orlOOLbs.  1 

II 

<S§w 

Apples  per  bbl                 

10  15 

$0.12% 

$0.12% 

$0  45 

Mavl. 

Bananas,  per  bunch  

.15 

.10 

.10 

Beef,  mutton,  pork  and  fresh 
meats,  per  Ib  

.00% 

.00% 

.00% 

Beer  and  ale,  per  bbl      

.25 

.25 

Beer  and  ale,  per  %  bbl  

.15 

.15 

Beer  and  ale,  per  J4  or  %  bbl. 

.10 

.10 

Beer  bottled  per  case 

10 

10 

Beer  bottled,  per  bbl  

20 

.20 

Berries,  fresh,  of  all  kinds, 

.00% 

.00% 

.00% 

Berries,  fresh,  of  all  kinds, 
per  stand  

10 

Butter  and  butterine,  per  Ib. 
(See  also  batter  freezing  rate.) 
Buckwheat  flour,  per  bbl  
Cabbage,  per  bbl  

•  OOM 

.15 
.25 

.00^ 

.12% 
.25 

.00% 

.10 
.20 

.50-75 
.50 

Jan.  1. 
Oct.l. 

Cabbage,  per  crate             .. 

10 

10 

08 

Calves  (per  day),  each  

10 

005S£ 

00% 

.00% 

Canned  and  bottled  goods,  per 
Ib  

0014. 

00% 

.00% 

Celery,  per  case  

\5 

.10 

iio 

OOH 

00^4 

.00% 

50-60 

Jan  1. 

Cherries  per  quart 

00*4 

00% 

00% 

Cider,  per  bbr   

'25 

.15 

.15 

Cigars  per  Ib                     . 

00% 

00  V 

00% 

Cranberries,  per  bbl           .... 

25 

!20 

.15 

Cranberries  per  case 

10 

Corn  meal,  per  bbl  

.16 

.12% 

.10 

Dried  and  boneless  fish,  etc., 
per  Ib                     ... 

00  1-5 

00% 

00% 

50 

Nov  1 

Dried  corn,  per  bbl  

12% 

10 

10 

Dried  and  evaporated  apples, 
perlb  

00% 

.00  1-10 

50 

Nov.  1 

Dried  fruit,  per  Ib 

00  1-6 

00% 

OOVa 

40-50 

Nov  1 

Eggs  per  case 

15 

12% 

10 

50-60 

Jan  J 

Figs,  per  Ib      

00% 

00% 

00  1-10 

Fish  per  bbl 

'20 

18 

15 

75 

Oct  1 

Fish,  per  tierce  

.15 

.13 

12% 

50 

Oct  1. 

(See  also  fish  freezing  rates.) 
Fruits,  fresh,  per  bbl  

.25 

.20 

.20 

Fruits,  fresh,  per  crate  

10 

08 

08 

Furs,    undressed,    hydraulic 
pressed,  per  Ib  

00% 

oou 

oou 

1  00 

Oct  1. 

Furs,  dressed,  per  Ib 

03 

02% 

02 

8  00 

Oct  1 

Ginger  ale,  bottled,  per  bbl.. 

.20 

15 

15 

Grapes,  per  Ib  

0014 

OOK 

OOii 

2  00 

Mavl. 

Grapes  per  basket 

03 

02 

'01 

334  MECHANICAL  REFRIGERATION. 

COLD  STORAGE  BATES  PER  MONTH— Continued. 


GOODS  AND  QUANTITY. 

First 
Month. 

1 

Each 
Succeeding 
Month. 

IP 
all 

Season  Rate 
per  Bbl. 
or  100  Lbs.  1 

fl      • 

®H 

QQ 

Grapes,  Malaga,  etc.,  per  keg. 
Hops,  per  Ib  

.15 
.OOM 
.25 
.26 
.15 
.20 
.00^ 
.014 
.00% 

:8* 

.25 
1.00 

:B* 
:Sf/s 

.05 
.50 
.10 
.20 
.40 
.00% 
.20 
.25 

.0014 
.25 
.20 
.25 
.15 
.30 
.0054 
.25 
.16 
.25 
.10 

.124 
.00  J4 
.20 
.20 
.12% 
.15 
.0014 
•01J4 
.004 
.00  1-5 
.15 
.20 
.80 
.OOH 
.124 
.10 
.124 
.04 
.40 
.08 
.16 
.30 
.OOM 
.15 
.20 

.00  Ys 
.20 
.15 
.20 
.124 
.25 

:§8* 

.10 
.25 
.10 

.12% 

y° 

.20 
.10 

•  1*4 

.001/8 

.01 

-00% 
.OOH 
.124 

Lard  per  tierce 

1.00 
1.00 
.50 

Nov.  1. 
Nov.  1. 
Nov.  1. 

Lard  oil  per  cask 

Macaroni,  per  bbl  

Maple  sugar,  per  Ib       .... 

.40-50 

Nov.  1. 

Maple  syrup,  per  gallon  

Meats,  fresh,  per  Ib  

Nuts  of  all  kinds,  per  Ib  
Oatmeal,  per  bbl  

.40-50 

Nov.  1. 

Oil,  per  cask      .... 

Oil,  per  hhd  

Oleomargarine,  per  Ib  

•T 

Onions,  per  bbl 

.50-60 

Mayl. 

Oranges,  per  box  

.10 

.50 

Nov.  1. 

Oysters,  in  tubs,  per  gal  
Oysters,  in  shell,  per  bbl  
Peaches,  per  basket  

.30 
.07 

"jj'.oo" 

.     .60 
1.20 
1.00 

Jan',  l".' 
Mayl. 
Mayl. 
Nov.  1. 

Pears,  per  box  .  .           .  . 

Pears  per  bbl 

Pigs'  feet,  per  Ib  

.0054 
.15 
.20 

:T 
:!f 

.10 
.20 
.0014 
.15 
.08 

Pork,  per  tierce 

Potatoes,  per  bbl    

Preserves,  jellies,  jams,  etc., 
per  Ib  

Provisions,  per  bbl 

Rice  flour  per  bbl 

Sauerkraut,  per  cask         .... 

.60-75 

Nov.  1. 

Sauerkraut,  per  4  bbl  
Syrup,  per  bbl  

1.00 

Oct.  1. 

Tobacco  per  Ib 

Vegetables,  fresh,  per  bbl  
Vegetables,  fresh,  per  case.  .  . 
Wine,  in  wood  per  bbl 

Wine,  in  bottles,  per  case  .... 

RATES   FOR    FREEZING   POULTRY,    GAME,    FISH,   MEATS, 
BUTTER,    EGGS,   ETC. 

The  rates  for  freezing  goods,  or  for  storing  goods  at 
a  freezing  temperature  when  they  are  already  frozen,  as 
follows: 

POULTRY,  GAME,  ETC. ,  IN  UNBROKEN  PACKAGES. 

Poultry,  including  turkeys,  fowl,  chickens,  geese, 
etc.,  and  rabbits,  squirrels  and  ducks  when  picked. 

Four  rates,  A,  B,  C  and  D,  for  storing  poultry,  and 
the  rate  to  be  charged  will  be  determined  by  the  amount 
of  such  goods  as  may  be  frozen  and  stored  during  a 
season  of  six  months,  usually  from  October  or  November 
1  to  April  or  May  1. 

RATE  A.— For  customers  storing  fifty  (50)  or  more 
tons  of  poultry,  the  rate  to  be  one-third  cent  per  pound  for 


APPENDIX  I.  335 

the  first  month  stored,  and  one-fourth  cent  per  pound 
for  each  month  or  fraction  of  a  month,  including  the 
first  month,  if  stored  for  more  than  one  month. 

BATE  B. — For  customers  storing  five  or  more,  but 
less  than  fifty  tons  of  poultry,  the  rate  to  be  one-third 
cent  per  pound  for  the  first  month  stored,  and  one-fourth 
cent  per  pound  for  each  month  or  fraction  of  a  month 
thereafter. 

BATE  C.— For  customers  storing  one  or  more,  but 
less  than  five  tons  of  poultry,  the  rate  to  be  three-eighths 
cent  per  pound  for  the  first  month  stored,  and  one- 
fourth  cent  per  pound  for  each  month  or  fraction  of  a 
month  thereafter. 

RATE  D.— For  customers  storing  less  than  one  ton 
of  poultry,  the  rate  to  be  one-half  cent  per  pound  for  the 
first  month  stored,  and  three-eighths  cent  per  pound  for 
each  month  or  fraction  of  a  month  thereafter. 

Venison,  etc.,  and  ducks  when  unpicked,  one  to  one- 
half  cent  per  pound  per  month,  according  to  quantity 
and  length  of  time  stored. 

Grouse  and  partridges,  three  cents  to  five  cents  per 
pair  per  month.  Woodcock,  one  cent  to  two  cents  per 
pair  per  month. 

Squabs  and  pigeons,  four  cents  to  six  cents  per  dozen 
per  month.  Quail,  plover,  snipe,  etc.,  three  cents  to  five 
cents  per  dozen  per  month. 

When  a  portion  of  the  goods  is  removed  from  a  pack- 
age, storage  to  be  charged  for  the  whole  package  as  it 
was  received  until  the  balance  of  the  package  is  removed 
from  the  freezer. 

For  goods  received  loose,  when  to  be  taken  out  of 
the  packages  in  which  they  are  received,  or  when  to  be 
laid  out,  the  following  rates  to  be  charged: 

Poultry,  including  turkeys,  chickens,  geese,  etc.,  and 
rabbits  and  squirrels,  one-half  cent  to  one-fourth  cent 
per  pound  extra,  according  to  quantity  and  length  of 
time  stored. 

Grouse,  partridges,  woodcock,  squabs,  pig'eons,  quail, 
plover  and  snipe,  50  per  cent  more  than  the  rates  as  above 
specified. 

Ducks  weighing  less  than  two  pounds  each,  two  cents 
to  three  cents  each  per  month.  Ducks  weighing  two 
pounds  or  more  each,  three  cents  to  four  cents  each  per 
month. 


336  MECHANICAL  REFRIGERATION. 

For  all  kinds  of  poultry  and  birds  not  herein  speci- 
fied, the  rate  from  one  cent  to  one-half  cent  per  pound 
per  month,  according  to  quantity  and  length  of  time 
stored. 

SUMMER  FREEZING  RATES. 

Freezing  rates  for  the  summer  months,  50  per  cent 
more  than  the  specified  winter  rates  for  the  first  month 
stored,  and  the  same  as  the  winter  rates  for  the  second 
and  succeeding  months. 

STORING  UNFROZEN  POULTRY,  ETC. 

For  holding  poultry,  game,  etc.,  which  are  not 
frozen,  at  a  temperature  which  shall  be  about  30°  F.,  the 
rate  to  be  one-fifth  cent  to  two-fifths  cent  per  pound,  ac- 
cording to  quantity,  for  any  time  not  exceeding  two  weeks. 

FREEZER  RATES  FOR  FISH  AND  MEATS. 

Salmon,  blue  fish  and  other  fresh  fish  in  packages, 
one-half  cent  per  pound  for  the  first  month  stored,  three- 
eighths  cent  per  pound  per  month  thereafter. 

Fresh  fish  of  all  kinds  when  to  be  hung  up  or  laid 
out,  three-fourths  cent  per  pound  for  the  first  month 
stored,  one-half  cent  per  pound  per  month  thereafter. 

Fish  in  small  quantities,  50  per  cent  more  than  the 
above  rates. 

Special  rates  for  large  lots  of  large  fish. 

Scallops,  three-fourths  cent  per  pound,  gross,  per 
month. 

Sweetbreads  and  lamb  fries,  one  cent  per  pound, 
gross,  per  month. 

Beef,  mutton,  lamb,  pork,  veal,  tongues,  etc.,  three- 
fourths  cent  to  one-half  cent  per  pound,  net,  for  the  first 
month  stored,  one-fourth  cent  to  three-eighths  cent  per 
pound  per  month  thereafter. 

BUTTER  FREEZING  RATES. 

For  freezing  and  storing  butter  in  a  temperature  of 
20°  F.  or  lower,  the  rate  to  be  charged  will  be  determined 
by  the  amount  of  such  goods  that  may  be  frozen  and 
stored  during  the  season  of  eight  months,  from  April  1 
to  December  1,  or  from  May  1  to  January  1.  There  will  be 
three  rates,  A,  B  and  C. 

RATE  A.— For  customers  storing  thirty-five  (35)  or  , 
more  tons  of  butter,  the  rate  to  be  fifteen  cents  per  100 
pounds,  net,  per  month. 


APPENDIX  I. 


337 


RATE  B. — For  customers  storing  five  or  more,  but 
less  than  thirty-five  tons  of  butter,  the  rate  to  be  eigh- 
teen cents  per  100  pounds,  net,  per  month. 

RATE  C.— For  customers  storing  less  than  five  tons 
of  butter,  the  rate  to  be  twenty-five  cents  per  100  pounds, 
net,  per  month. 

EGG  FREEZING   RATES. 

For  freezing  broken  eggs  in  cans,  the  charge  to  be 
one-half  cent  per  pound,  net  weight,  per  month,  and  for 
a  season  of  eight  months  the  rate  to  be  one  and  one-half 
cents  per  pound,  net  weight. 

RENT  OF  ROOMS. 

For  freezing  temperatures,  four  cents  to  five  cents 
per  cubic  foot  per  month. 

TERMS  OF    PAYMENT  OF  COLD  STORAGE   AND  FREEZING 
RATES. 

All  the  above  rates  are  the  charges  for  each  month, 
or  fraction  of  a  month,  unless  otherwise  specified;  and 
in  all  cases,  fractions  of  months  to  be  charged  as  full 
months. 

Charges  to  be  computed  in  all  cases  when  possible 
upon  the  marked  weights  and  numbers  of  all  goods  at 
the  time  they  are  received. 

All  storage  bills  are  due  and  payable  upon  the  deliv- 
ery of  a  whole  lot,  or  balance  of  a  lot  of  goods,  or  every 
three  months,  when  goods  are  stored  more  than  three 
months. 

Unless  special  instructions  regarding  insurance  ac- 
company each  lot  of  goods,  they  are  held  at  owner's  risk. 

DESCRIPTION  OF  TWO-FLUE  BOILERS. 


NUMBER. 

1 

2 

3 

4 

5 

6 

Heating  Surface,  square  feet. 
Horse  power  at  10  square  feet. 
Diameter,  inches.  -  

105 
10 
30 
10 

10 

M 

% 

15x15 
30 
3 
4 
6 

lX/2 
1» 

15 
30 
16 
2100 
4400 

152 
15 
32 
14 
10 
K 
% 
15x15 
32 

P 

6 

J" 

15 

30 
16 

2580 
5100 

201 
20 
36 
16 
12 

* 

18x18 
36 
4 
6 
6 

\A 

18 
30 
16 
3300 
6400 

249 
25 

40 
18 
13 

& 
% 
20x20 
40 
4 
6 
6 

j* 

18 
35 
16 
4250 
7350 

356 
36 
44 
22 
15 

H 

% 

24x24 
44 

r 

ll/2 

4* 

40 
16 
5225 

8800 

508 
51 
50 
28 
18 
5-16 
7-16 
30x30 
60 
5 
8 
7 
2 
3 
26 
50 
16 
10000 
15000 

Length  feet                            .  . 

Diameter  of  Flues,  inches  .  .  . 
Thickness  of  Shell,  inches..  . 
Thickness  of  Head,  inches  .  .  . 
Size  of  Dome,  inches  

Width  of  Grate  Bars,  inches  . 
Length  of  Grate  Bars,  feet.    . 
Number  of  Wall  Binding  Bars 
Length  Wall  Binding  Bars,  ft. 
Diameter  of  Blow-off  Cock,  ins 
Diameter  of  Safety  Valve,  ins 
Diameter  of  Smoke  Stack,  ins 
Length  of  Stack,  feet  
Number  of  Iron  in  Stack  
Approximate  Weight  of  Boiler 
Total  Weight 

338 


MECHANICAL  REFRIGERATION. 


USEFUL  NUMBERS  FOR   RAPID  APPROXIMATION. 

Feet X  .00019  =miles. 

Yards X  .0006  =miles. 

Links X  .22  =yards. 

Links X  .66  =feet. 

Feet X  1.5  =links. 

Square  inches X  .007  =square  feet. 

Circular  Inches X  .00546  =squarefeet. 

Square  feet X  .111  =square  yards. 

Acres X  4840.  =square  yards. 

Square  yards X  .0002066=acres. 

Cubic  feet X  .04  =cubic  yards. 

Cubic  inches X  .00058  =cubic  feet. 

U.  S.  bushels X  .046  =cubic  yards. 

U.S.  bushels X  1.244  = cubic  feet. 

U.  S.bushels X  2150.42  =cubic inches. 

Cubic  feet X  .8036  =U.  S.  bushels. 

Cubic  inches X  .000466  =U.  S.  bushels. 

U.S.  gallons X  .13368  =  cubic  feet.       i 

U.S.gallons X  231.  =cubic  inches. 

Cubic  feet X  7.48  =U.  S.  gallons. 

Cylindrical  feet X  5.878  =U.  S.  gallons. 

Cubic  inches X  .004329  =U.  S.  gallons. 

Cylindrical  inches X  .0034  =D.  S.  gallons. 

Pounds X  .009  =cwt.(1121bs.) 

Pounds X  .00045  =  tons  (2,240  Ibs.) 

Cubic  feet  water X  62.5  =lbs.  avdps. 

Cubic  inches  water. X  .03617  =lbs.  avdps. 

Cylindrical  feet  of  water X  49.1  =lbs.  avdps. 

Cylindrical  inches  of  water X  .02842  =lbs.  avdps. 

U.  S.  gallons  of  water -r-  13.44  =cwt.  (112  Ibs.) 

U.  S.  gallons  of  water -f-  268.8  =tons. 

Cubic  feet  water •*•  1.8  =cwt.  (1121bs.) 

Cubic  feet  water -4-  35.88  =tons. 

Cylindrical  feet  of  water -*-  5.875  =U.  S.  gallons. 

Col.  of  water  12  in.  high,  1  in.  diam. . .  =  .34  Ibs. 

183  346  circular  inches =1  square  foot. 

2,200  cyclindrical  inches =1  cubic  foot. 

French  meters X  3.281  =feet. 

Kilogrammes X  2.205  =avdps.lbs. 

Grammes X  .0022  =avdpslbs. 


12  X  wt.  of  pine  pattern  =  iron  casting. 

13  X  wt.  of  pine  pattern  =  brass  casting. 
19     X  wt.  of  pine  pattern  =  lead  casting. 
12.2  x  wt.  of  pine  pattern  =  tin  casting. 
11.4  X  wt.  of  pine  pattern  =  zinc  casting. 
1  cubic  foot  anthracite  coal  =  54  Ibs. 

40— 43  cubic  feet  anthracite  coal  =  1  ton. 

49  cubic  feet  bituminous  coal  =  1  ton. 

537  Ibs.  per  cubic  foot  =  wt.  of  copper- 

450  Ibs.  per  cubic  foot  =  wt.  of  cast  Iron. 

485  Ibs.  per  cubic  foot  =  wt.  of  wrought  iron. 

708  Ibs.  per  cubic  foot  =  wt.  of  cast  lead. 

490  Ibs.  per  cubic  foot  =  wt.  of  steel. 

1  gallon  water  =  8^  Ibs.  =  231  cubic  inches. 

1  cubic  foot  water  =  62>4  Ibs.  =  7H  gallons. 

1  Ib.  water  =  27.8  cubic  inches  =  1  pint. 

The  friction  of  water  in  pipes  is  as  the  square  of  its  velocity. 

Doubling  the  diameter  of  a  pipe  increases  its  capacity  four 
times. 

In  tubular  boilers,  15  square  feet  of  heating  surface  are  equiv- 
alent to  one  horse  power;  in  flue  boilers,  12  square  feet  of  heating 
surface  are  equivalent  to  one  horse  power;  in  cylinder  boilers,  10 
square  feet  of  heating  surface  are  equivalent  to  one  horse  power. 

One  square  foot  of  grate  will  consume,  on  an  average,  12  Ibs.  of 
coal  per  hour. 

Consumption  of  coal  averages  7^  Ibs.  of  coal,  or  15  Ibs.  of  dry 
pine  wood,  for  every  cubic  foot  of  water  evaporated. 

The  ordinary  speed  to  run  steam  pumps  is  at  the  rate  of  100  feet 
piston  travel  per  minute. 


APPENDIX  I. 


339 


r 
C,        ^, 


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nternal 
q.  Inch. 


External 
Sq.  Inch 


rn 
he 


Externa 
Inches. 


gss 


Act 
nte 
Inc 


Actual 
Externa 
Inches. 


Nomina 
Internal 
Inches. 


O  CO  OS  C 


SSss 


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lls? 


SS3S 


icgao 


SS85 


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05  00  00  >0 


lls 


igjO 


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340 


MECHANICAL  REFRIGERATION. 


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APPENDIX  I. 


341 


TABLE  OF  MEAN  TEMPERATURE  OF  DIFFERENT  LOCALI- 
TIES,  DEGREES  FAHR. 


LOCATION. 

i 

>H 

b| 

a 

I 

CO 

Summer. 

Autumn. 

Winter. 

Algiers                    . 

63  0 

63  0 

74  5 

70  5 

50  4 

Berlin         

47  B 

46  4 

63  1 

47  8 

30  6 

Berne   

46.0 

45.8 

60  4 

47.3 

30.4 

Boston          

49  0 

48 

66 

53 

28 

Baltimore 

64  9 

60  0 

83  0 

64  6 

43  5 

Buenos  Ayres  

62  5 

59  4 

73  0 

64  H 

52  6 

Cairo 

72  3 

71  6 

84  6 

74  3 

58  5 

Calcutta.    .        

78  4 

82  6 

83  3 

80  0 

67  8 

69  8 

69  8 

82  0 

72  9 

54  8 

Christiania.        ... 

41  7 

39  2 

59  5 

42  4 

25  2 

Cape  of  Good  Hope 

66  4 

63  5 

74  1 

66  9 

58  6 

Constantinople        .... 

56  7 

51  8 

73  4 

60  4 

40  5 

46  8 

43  7 

63  0 

48  7 

31  3 

Chicago              

45  9 

52  8 

74  6 

61  2 

38  4 

Cincinnati  

54  7 

63.2 

81.8 

6t5.4 

46  6 

Edinburgh                 

47  5 

45  7 

57  9 

48  0 

38  5 

62  2 

60  6 

72  6 

66  3 

49  6 

Jamaica  (Kingston)  
Lima  (Peru) 

79 

66  2 

78.3 
63  0 

81.3 
73  2 

80 
69  6 

76.3 
59  0 

Lisbon.  .             

61  5 

59  9 

71  1 

62  6 

52  3 

50  7 

49  1 

62  8 

51  3 

39  6 

Madeira  (Funchal)  

65  7 

6H  5 

70 

67  6 

61  3 

Madrid 

57  g 

57  6 

74  1 

56  7 

42  1 

Mexico  City    

60  5 

53  6 

63  4 

65  2 

60  1 

Montreal 

43  7 

44  2 

69  1 

47  1 

17  5 

Moscow  

38  5 

43  3 

62  6 

34  9 

13  5 

Naples 

61  5 

59  4 

74.  g 

62  2 

49  6 

New  Orleans  

72 

73 

84 

72 

58 

New  York 

53 

50 

72 

56 

33 

New  Zealand  

59  6 

60  1 

66  7 

58  0 

53  5 

Nice                      

60  1 

65  9 

72  5 

63  0 

48  7 

Nicolaief  (Russia) 

48  7 

49  3 

71  2 

50 

25  9 

Paramatto  (Australia)...  . 

64  6 

66  6 

73  9 

64  8 

54  5 

Palermo  

63 

59  0 

74  3 

66  2 

62  5 

Pekin  (China)              

52  6 

56  6 

77  8 

54  9 

29 

Paris 

51  4 

50  5 

61  6 

52  2 

'37  9 

Philadelphia 

55 

52 

76 

67 

34 

Quito  (Equador)  
Quebec         

60.1 
40  3 

60.3 

60.1 

62.5 

59.7 

Rio  Janeiro 

73  6 

72  5 

79  0 

74  5 

68  5 

Rome  

59.7 

57  4 

73  a 

61  7 

46  6 

San  Francisco 

57  5 

58 

59 

60 

53 

St.  Louis  

55  0 

84  6 

67  8 

44.6 

4H  0 

St  Petersburg 

38  3 

35  1 

60  3 

40  5 

16  6 

Stockholm  

42.1 

38  3 

61  0 

43  7 

25  5 

Trieste.    ... 

55  8 

53  8 

71  5 

56  7 

39  4 

Turin 

53  1 

53  1 

71  6 

53  8 

33  4 

Vienna.       .        ...          ... 

50  7 

49  1 

62  8 

51  3 

39  6 

Warsaw 

45  5 

44  6 

63  5 

46  4 

97  5 

Washington  

59 

69 

79 

58 

38 

USEFUL  DATA  ABOUT  LIQUIDS. 

A  gallon  of  water  contains  231  cubic  inches,  and 
weighs  8i  pounds  (U.  S.  standard). 

A  cubic  foot  of  water  contains  7^  gallons,  and  weighs 
pounds. 

One  U.  S.  gallon=.133  cubic  feet;  .83  imperial  gal- 
Ion;  3.8  liters. 


342  MECHANICAL  REFRIGERATION. 

An  imperial  gallon  contains  277.274  cubic  inches.  .16 
cubic  feet;  10.00  pounds;  1.2  U.  S.  gallons;  4.537  liters. 

A  cubic  inch  of  water=.03607  pound;  .003607  impe- 
rial gallons;  .004329  U.  S.  gallon. 

A  cubic  foot  of  water  =6.23  imperial  gallons;  7.48 
U.  S.  gallons;  28.375  liters;  .0283  cubic  meters;  62.35 
pounds;  557  cwt.;  .028  ton. 

A  pound  of  water  =  27.72  cubic  inches;  .10  imperial 
gallon;  .083  U.  S.  gallon;  .4537  kilos. 

One  cwt.  of  water  =  11.2  imperial  gallons;  13.44  U. 
S.  gallons;  1.8  cubic  foot. 

A  ton  of  water  =  35.9  cubic  feet;  224  imperial  gallons; 
298.8  gallons;  1,000  liters  (about);  1  cubic  meter  (about). 

A  liter  of  water  =  .220  imperial  gallon:  .264  U.  S. 
gallon;  61  cubic  inches;  .0353  cubic  foot. 

A  cubic  meter  of  water  =  220  imperial  gallons;  264 
U.  S.  gallons;  1.308  cubic  yards;  61,028  cubic  inches; 
35.31  cubic  feet;  1,000  kilos;  1  ton  (nearly);  1,000  liters. 

A  kilo  of  water  =  2.204  pounds. 

A  vedros  of  water  =  2.7  imperial  gallons. 

An  eimer  of  water  =  2.7  imperial  gallons. 

A  pood  of  water  =  3.6  imperial  gallons. 

A  Russian  fathom  =  7  feet. 

One  atmosphere  =  1.054  kilos  per  square  inch. 

One  ton  of  petroleum  =  275  imperial  gallons  (nearly). 

One  ton  of  petroleum  =  360  U.  S.  gallons  (nearly). 

A  column  of  water  1  foot  in  height  =  .434  pound 
pressure  per  square  inch. 

A  column  of  water  1  meter  in  height  =  1.43  pounds 
pressure  per  square  inch. 

One  pound  pressure  per  square  inch  =  2.31  feet  of 
water  in  height. 

One  U.  S.  gallon  of  crude  petroleum  =  6.5  pounds 
(nearly). 

•    One  wine  gallon,  or  U.  S.  gallon,  Is  equal  to  8.331  pounds=3,785 
cubic  centimeters=58,318  grains. 

One  imperial   gallon  (English  gallon)  is  equal  to  about  ten 
pounds=4.543  cubic  centimeters =70,000  grains. 

One  grain=0.0649  grams— one  gram= 15.36  grains. 

One  barrel=1.192  hectoliters— one  hectoliter=0.843  barrels. 

One  English  quarter=eight  bushels =290.78  liters. 

One  English  bushel=36.35  liters=0.3635  hectoliters. 

One  English  barrel =36  gallons.     One  American  barrel =31  gals. 

One  bushel  malt  (English),  40  pounds;  American,  34  pounds  (32 
pounds  cleaned);  one  bushel  barley  (American),  38  pounds. 

One  kilogram  square  centimeter  equal  to  14.2  pounds  inch 
pressure  (equal  to  about  one  atmosphere). 

Four  B.  T.  units  equal  to  about  one  calorie. 


APPENDIX  I.  343 

TEMPERATURES— FAHRENHEIT  AND  CENTIGRADE. 


•jr. 

-c. 

•F. 

«G 

"F. 

«C. 

"F. 

"C. 

op 

"C. 

•F.|     °C.     ; 

330 

165.6 

267 

130.6 

206 

96.7 

143 

61.7 

80 

26  7 

19 

-  7.2 

329 

165. 

266 

130. 

205 

96.1 

142 

61.1 

79 

26.1 

18 

—  78 

328 

164.4 

265 

Ii9.4 

204 

95.6 

141 

60.6 

78 

25.6 

17 

—  8.3- 

327 

163.9 

264 

128.9 

203 

95 

140 

60 

77 

25. 

16 

—  8.9 

326 

163.3 

2*i:; 

128.3 

202 

94.4 

139 

59  4 

76 

24  4 

15 

—  9.4 

325 

162.8 

2(12 

127.8 

201 

93.9 

138 

58.9 

75 

23.9 

14 

—10. 

324 

162.2 

261 

127.2 

200 

93  3 

137 

58.3 

74 

23.3 

13 

—10-6 

323 

161.7 

2<;o 

126.7 

19!) 

92.8 

136 

57.8 

73 

22.8 

12 

—11.1 

322 

161.1 

25!) 

126.1 

198 

92.2 

135 

57.2 

72 

22.2 

n 

-11.7 

321 

160.6 

25S 

125.6 

197 

91  7 

134 

56  7 

71 

21.7 

10 

-12.2 

320 

160. 

257 

125. 

190 

91  1 

133 

56.1 

70 

21  1 

9 

—12.8 

319 

159.4 

256 

124.4 

195 

90.6 

132 

55.6 

69 

20.6 

8 

—13.3 

318 

158.9 

255 

123.9 

194 

90. 

131 

55. 

68 

20. 

7 

-13.9 

317 

158.3 

123.3 

L93 

89.4 

1HO 

54.4 

67 

19  4 

6 

-14.4 

316 

157.8 

253 

122.8 

192 

.88.9 

12!) 

53.9 

66 

18.9 

5 

-15. 

315 

157.2 

252 

122.2 

191 

88.3 

12X 

53.3 

65 

18.3 

4 

—  15.6 

314 

156.7 

251 

121.7 

190 

87.8 

127 

52.8 

64 

17'.  8 

3 

—16.1 

313 

156.1 

250 

121.1 

1X9 

87.2 

126 

52.2 

63 

17.2 

2 

-16  7 

312 

155.6 

24!) 

120.6 

1XX 

86.7 

125 

51  7 

62 

16.7 

1 

-1-7.2 

311 

155. 

24S 

120. 

1X7 

86.1 

124 

51.1 

61 

16.1 

0 

—17.8 

310 

154,4 

247 

119.4 

1X6 

85.6 

123 

50  6 

60 

15  6 

—  1 

-18.3 

30!) 

133*9 

24i  ; 

118.9 

1X5 

85. 

122 

50. 

59 

15 

—  2 

-18.9 

308 

153.3 

245 

118.3 

1*1 

84.4 

121 

49.4 

58 

14  4 

-  3 

-19  4 

307 

152.8 

244 

117.8 

1X3 

83  9 

120 

48.9 

57 

13.9 

—  4 

-20 

306 

152.2 

243 

117.2 

1S° 

83.3 

11!) 

48'.  3 

56 

13  3 

—  5 

-20.6 

305 

151.7 

242 

116.7 

181 

82.8 

118 

47.8 

55 

12.8 

-  6 

-21.1 

304 

151.1 

241 

116.1 

180 

82.2 

117 

47.2 

54 

12.2 

—  7 

-21.7 

303 

150.6 

240 

115.6 

179 

81.7 

11(1 

46.7 

53 

11.7 

-  8 

-22.2 

302 

150. 

239 

115. 

178 

81.1 

115 

46  1 

52 

11.1 

—  9 

-22.8 

301 

149.4 

114.4 

177 

80,6 

114 

45.6 

51 

10.6 

-10 

-23.3 

300 

148.9 

237 

113.9 

17'i 

80. 

113 

45. 

50 

10. 

—11 

—23  9 

299 

148.3 

236 

113.3 

175 

79.4 

112 

44.4 

49 

9  4 

—  12 

-24  4 

298 

147.8 

285 

112.8 

174 

78.9 

111 

43.9 

48 

8.9 

-13 

-25. 

297 

147.2 

234 

112.2 

173 

78.3 

110 

43.3 

47 

8.3 

-14 

-25  6 

296 

146.7 

233 

111.7 

172 

77.8 

109 

42.8 

46 

7.8 

—15 

--26  1 

295 

146.1 

232 

111.1 

171 

77.2 

108 

42  2 

45 

7.2 

-16 

-26.7 

294 

145.6 

231 

110.6 

170 

76.7 

107 

41.7 

44 

a.  7 

-17 

-27.2 

293 

145. 

230 

110. 

16!) 

76.1 

10(1 

41.1 

43 

6.1 

-18 

-27.8 

292 

144.4 

22!) 

109.4 

1(18 

75.& 

105 

40.6 

42 

5.6 

-19 

—  £8.3 

J291 

143.9 

228 

108.9 

167 

75. 

104 

40. 

41 

5 

-20 

-28.9 

290 

143.3 

227 

108.3 

]M 

74.4 

103 

39  4 

40 

4.4 

-21 

-29.4 

289 

142.8 

"26 

107.8 

1(>5 

73.9 

102 

38.9 

39 

3.9 

-22 

288 

142.2 

225 

107.2 

1(14 

73.3 

101 

38  3 

38 

3.3 

-23 

js&Iot'O 

287 

141.7 

224 

106.7 

1(13 

72.8 

100 

37.8 

37 

2.8 

-24 

—  Slla% 

286 

141.1 

223 

106.1 

1(12 

72.2 

99 

37.2 

36 

••  2  2 

-25 

—  31  7 

285 

140.6 

222 

105.6 

161 

71.7 

98 

36  7 

35 

1.7 

-26 

-32  2 

284 

140. 

221 

105 

160 

71.1 

97 

36  1 

34 

1.1 

—  2T 

-32.8 

283 

139.4 

220 

104.4 

159 

70.6 

96 

35.6 

33 

0.6 

-28 

-33.3 

282 

138.9 

219 

103.9 

158 

70. 

95 

35. 

Water  freezes 

—29 

—33.9 

281 

138.3 

218 

103.3 

157 

69.4 

94 

34.4 

0£>                 f\ 

-30 

-34.4 

280 
279 

137r8 
137,2 

217 

216 

102.8 
102.2 

156 
155 

68.9 
68.3 

93 
92 

33.9 
33.3 

oJ         U. 

=1 

i-35. 
-35/6 

31 

—  0.6 

278 

136.7 

215 

101.7, 

154 

67.8 

91 

32.8 

30 

—  1.1 

-33 

—36.1 

277 

136.1 

214 

101.1 

153 

67.2 

90 

32.2 

29 

—  17 

—34 

—36  7 

276 

«)*7C 

135.6 

11C 

213J 

100.6 

152 
i  £i 

66-.7 

C£     1 

X!) 

31.7 

•M       1 

28 

—  2.2 

2Q 

—35 

-37.2 

410 

274 

1J5. 

134.4 

Water  boils 

151 

150 

bo.  1 
65.6 

87 

dl.l 

30.  6. 

26 

-  3.3 

—36 
—37 

—  37.  H 
—38.3 

273 

133.9 

212   100. 

149 

65. 

86 

30. 

25 

—  3.9 

38  9 

272 

133.3 

211    99.4 

148 

64.4 

85 

29.4 

24 

—  4.4 

—39 

—39.4 

271 

132.8 

210    98.9 

147 

63.9 

84 

28.9 

23 

-  5 

270 
269 

132.2 
131.7 

209    98.3 
208    97.8 

14(i 
145 

63.3 

62.8 

83 
82 

28.3 

27.8 

22 
21 

—  5.6 
—  6.1 

Mercury  freezes 

26b 

131,1 

207    97.2 

144 

62.2 

81 

27.2 

20 

-8.3 

—  40—  40.  j 

344 


MECHANICAL  REFRIGERATION. 


SPECIFIC  GRAVITY  TABLE  (BEAUME). 

The  meaning  of  the  degrees  of  the  Beaume  scale  for 
liquids  heavier  than  water  has  been  defined  somewhat 
differently  by  the  manufacturing  chemists  of  the  United 
States.  Accordingly  the  specific  gravity  for  any  given 
degree  Beauine"  is  found  after  the  formula: 

145 
Specific  gravity=145_deg  Beaum<§. 

The  following  table  is  calculated  after  this  formula 
by  Clapp: 


Degrees. 

Specific 
Gravity. 

Degrees. 

Specific 
Gravity. 

Degrees. 

Specific 
Gravity. 

0 

1.000 

18 

1.142 

45 

1.450 

1 

1.007 

19 

1.151 

50 

1.526 

2 

1.014 

•20 

1.160 

55 

1.611 

3 

1-.021 

21 

1.169 

60 

1.706 

4 

1.028 

22 

1.179 

65 

1.812 

5 

1.036 

23 

1.188 

70 

1.933 

6 

1.043 

24 

1.198 

7 
8 
9 

1.051 
1.058 
1.066 

25 
26 

27 

1.208 
1.218 
1.229 

66 
Used  by 
sulphuric 
acid  man- 
u  f  a  ctur- 
ers. 

1.835 

10 

1.074 

28 

1.239 

11 

1.082 

29 

1.250 

12 

1.090 

30 

1.261 

13 

1.098 

32 

1.283 

14 

1.107 

34 

1.295   ' 

15 

1.115 

36 

1.306 

16 

1.124 

38 

1.318 

17 

1.133 

40 

1.381 

APPENDIX  I.  345 

TABLE  ON  SOLUTIONS  OF  CHLORIDE  OF  CALCIUM. 


Specific 
Gravity 
at  84°  F. 

Degree 
Beaum6 
at  64°  F. 

Degree 
Salometer 
at  64°  F. 

Per  Cent 
of 
Chloride 
of 
Calcium. 

Freezing 
Point. 
Deg.  F. 

Ammonia 
Gauge. 

Pounds  per 
Square  Inch  at 
Freezing  Point. 

1.007 

1 

4 

0.943 

+31.20 

46 

1.014 

2 

8 

1.886 

+30.40 

45 

1.021 

3 

12 

2.829 

+29.60 

44 

1.028 

4 

16 

3.772 

+28.80 

43 

1.035 

5 

20 

4.715 

+28.00 

42 

1.043 

6 

24 

5.658 

-26.89 

41 

1.050 

7 

28 

6.601 

-25.78 

40 

1.058 

8 

32 

7.544 

-24.67 

38 

1.065 

9 

34 

8.487 

-23.56 

37 

1.073 

10 

40 

9.430 

-22.09 

35.5 

1.081 

11 

44 

10.373 

h20.62 

34 

1.089 

12 

48 

11.316 

-19.14 

32.5 

1.097 

13 

52 

12.259 

-17.67 

30.5 

1.105 

14 

56 

13.202 

-15.75 

29 

1.114 

15 

60 

14.145 

-13.82 

27 

1.112 

16 

64 

15.088 

[-11.89 

25 

1.131 

17 

68 

16.031 

-  9.96 

23.5 

1.140 

18 

72 

16.974 

-  7.68 

21.5 

1.149 

19 

76 

17.917 

-  5.40 

20 

1.158 

20 

80 

18.860 

-  3.12 

18 

1.167 

21 

84 

19.803 

—  0.84 

15 

1.176 

22 

88 

20.746 

-  4.44 

12.5 

1.186 

23 

92 

21.689 

—  8.03 

10.5 

1.196 

24 

96 

22.632 

—11.63 

8 

1.205 

25 

100 

23.575 

—15.23 

6 

1.215 

26 

104 

24.518 

—19.56 

4 

1.225 

27 

108 

25.461 

—24.43 

1.5 

1.236 

28 

112 

26.404 

—29.29 

L  "  Vacuum 

1.246 

29 

116 

27.347 

—35.30 

5  " 

1.257 

30 

120 

28.290 

—41.32 

8.5  " 

1.268 

31 

29.233 

—47.66 

12  " 

1.279 

32 

30.176 

—  54  .  00 

15  " 

1.290 

33 

31.119 

—  44.32 

10  " 

1.302 

34 

32.062 

—  34  66 

4  " 

1.313 

35 

33 

—25.00 

1.5  Ibs. 

This  table,  which  has  been  published  by  a  manu- 
facturer of  chloride  of  calcium,  gives  the  freezing  points 
much  lower  in  some  cases  than  the  small  table  on  page 
142. 


346 


MECHANICAL  REFRIGERATION. 


FRICTION  OF  WATER  IN  PIPES. 

Frictional  loss  in  pounds  pressure  for  each  100  feet  in 
length  of  cast  iron  pipe  discharging  the  stated  quanti- 
ties per  minute: 


<33* 
37$ 

£ 

830 
k°37. 


1867 
•P75 
0490 
«9°5 

K 


SUBS  OP  PJPES,  INSIDE  DIAMETER. 


%, 


j| 
«9.oo 

aj.5 


H.OS 

•438 


.•• ".  i 
•47 


3.62 
3  75 


82^.40 

iL 


\i.a6 

a;oi 

2-44 

.W 

M-9 

281 

37-5 
47-7 


.-  '•?' 


S3 


28.06 
33- 4^ 
42.96 


:35 
•74 

1.31 


3-85 
7.76 

11.20 
15.20 
19.50 
25.00 
•30,80 


:* 

3-65 
4-73 
6.01 
7 '43 


III 


.910 


365 


38 


.& 


The  frictional  loss  is  greatly  increased  by  bends  or 
irregularities  in  the  pipes. 


COMPARISON  OF 

Acceleration  of  gravity 

Acceleration  of  gravity 

1  dyne     . 

1  dyne 

1  grain    . 

1  gram    . 

1  pound  avdp. 

1  foot  pound 

1  foot  pound 

1  foot  pound 

1  metric  horsepower  hour 

1  metric  horsepower  hour 

1  metric  horsepower  hour 

3  metric  horsepower  hour 

1  metric  horsepower  hour 

1  horsepower  hour 

1  horsepower  hour 

1  horsepower  hour 

1  horsepower  hour 

1  horsepower  hour 


UNITS  OF  ENERGY  (BERING.) 

=        981.000         centimeters  per  second. 
=         32.186        feet  per  second. 

.015731    grain. 

.0010194  gram. 
=  63.668  dynes. 
=  981.  dynes. 

=  444976.  dynes. 

.0012953  pound  Fah.,  heat  unit. 

.007196    pound  C.,  heat  unit. 

.0003264  kilogr.-C.,  heat  unit. 


=  1952940. 
=  270000. 
=   2529.7 
=   1405.4 

.98634 
=  2685400. 
-1980000. 
=   2564.8 
=   1424.9 
=    646.31 


foot  pounds, 
kilogram  meters, 
pound  Fah.,  heat  units, 
pound  C.,  heat  units, 
horsepower  hour, 
joules. 
foot  pounds, 
pound  Fah.,  heat  units, 
pound  C.,  heat  units. 
kilogr.-C.,  heat  units. 


APPENDIX  I. 


347 


COMPARISON  OF  UNITS  OF  BNBBGY  (BERING). 

1  pound  Fahrenheit    . 

1  pound  Fahrenheit    . 

1  pound  Fahrenheit   . 

1  pound  Fahrenheit   . 

1  pound  Fahrenheit   . 

1  pound  Fahrenheit   . 

1  pound  Fahrenheit   . 

1  pound  Centigrade 

1  pound  Centigrade 

1  pound  Centigrade 

1  pound  Centigrade 

1  pound  Centigrade 

1  pound  Centigrade 

1  kilogram  Centigrade 

1  kilogram  Centigrade  — 

1  kilogram  Centigrade   = 

1  kilogram  Centigrade   =" 

1  kilogram  Centigrade  = 

1  watt-hour 

1  watt-hour 

1  watt-hour 

1  erg 

1  erg 

1  gram  centimeter 

1  Joule 

1  volt-coulomb 

1  watt  during  every 
second 

1  volt  ampere  dur- 
ing every  second 

1  volt  ampere  dur- 
ing every  second 

1  foot-pound 

1  foot-pound 

1  foot-pound 


=       1047.03 

joules. 

=        772. 

foot  pounds. 

=         106.731 

kilogram  meter. 

.56556 

=              .25300 

pound  Centigrade, 
kilogram  Centigrade. 

.29084 

watt-hour. 

1 

Brit,  therm,  unit  (B.T.TJJ 

= 

1884.66 
1389.6 

foot  pounds. 

!l 

192.116 

kilogram  meters. 

__ 

1.8 

pound  Fahrenheit. 

= 

.62352 

watt-hour. 

Z 

.0007018 
3063.5 

horsepower  hour, 
foot  pounds. 

=. 

423.54 

kilogram  meters. 

= 

3.9683 

pound  Fahrenheit. 

= 

1.1542 

watt-hours. 

_ 

.0015472 

horsepower  hour. 

_ 

3600. 

joules. 

= 

2654.4 
3.4383 

foot  pounds. 

— 

1. 

dyne-centimeter. 

a 

.0000001 

joules. 

= 

981.00 

ergs. 

B 

10000000. 

ergs. 

= 

.737324 

foot  pound. 

.101937      Kilogram  meter. 
.0013406    horsepower  for  one  sec. 


.0009551 
-  13562600. 

1.35626 
=   13825. 


1  foot-pountk  — 

1  horsepower 
1  horsepower 
1  horsepower 
1  horsepower        .          ™ 
1  Ib.  F.  heat  unit  per  min  = 
1  Ib.F.  heat  unit  per  min  _ 
1  Ib.F.  heat  unit  per  min = 
1  Ib.  Ct.  heat  unit  per  min  = 
1  k.  Ct.  heat  unit  per  min  = 
1  Pferdekraft  = 

1  erg  per  second  = 

1  watt  = 

1  volt  ampere  = 

1  volt  coulomb  per  sec.  =- 
1  volt  coulomb  per  sec.  = 
1  foot  pound  per  min.    = 
1  foot  pound  per  min.    ° 
1  foot  pound  per  min.    - 
1  metric  horsepower 
1  French  horsepower 
1  chevalvapeur 
1  force  de  cheval  _ 

1  horsepower  — 

1  horsepower  — 

1  horsepower  =• 

1  horsepower  = 

1  ton  of  ref rig.  capacity = 


.0018434 
745.941 


42.746 
1.01385 

17.4505 
.033718 
.023394 
.043109 


pound  F.  heat  unit. 

ergs. 

joules. 

kilogram  meter. 

metric    horsepower  for 

one  second, 
watts. 

foot  pounds  per  minute. 
Ib.  P.,  heat  unit  per  min. 
metric  horsepowers, 
watts. 

metric  horsepower, 
horsepower, 
horsepower, 
horsepower, 
klg.  cent, 
watt. 

ergs  per  second, 
foot  pounds  per  min. 
Ib.  F.  heat  unit  per  min. 
horse  power,, 
watt. 

metric  horsepower. 
.000030303  horsepower. 
735.75x107      ergs  per  second. 

foot  pounds  per  minute. 
Ib.  F.  heat  units  per  min. 
Ib.  Ct.  heat  unit  per  min. 
foot  pounds  per  minute, 
foot  pounds  per  hour. 
H.  units  per  kour  (B.T.  units). 
B.  T.  units  per  minute. 
B.  T.  units. 


10.625 

.0000001 
10000000. 
412394. 

.0573048 
.0013400 
.0326043 
.00003072 


82549.0 
42.162 


33000. 
1980000. 
2565. 

43.75 
284000. 

1  ton  of  refrig.  capacity =  to  about  H-ton  ice 
1  ton  of  ref.  cap.  per  day  =  to  about  12000  B.  T.  units  per  hour. 
1  ton  of  ref.  cap.  per  day  =>  to  about    200  B.  T.  units  per  minute. 

In  these  tables  the  mechanical  equivalent  of  heat  is 
taken  at  772.  Many  engineers  prefer  the  more  recent 
figure,  778. 


348  MECHANICAL  REFRIGERATION. 

TABLE  OF  MEAN  EFFECTIVE  PRESSURES. 


The  above  graphical  table  will  be  found  of  assistance 
to  the  engineer  by  affording  a  ready,  and,  at  the  same 
time,  comprehensive  means  of  ascertaining  the  mean 
effective  pressure  of  steam  in  an  engine  cylinder,  when 
the  initial  steam  pressure  and  the  point  of  cut-off  or 
the  number  of  expansions  of  the  steam  are  known. 

AMMONIA  COMPRESSION  UNDER  DIFFERENT  CONDITIONS. 


WetQas. 

Dry  Gas. 

Condenser  pressure  

113.3 
15.6 
69.2' 
.5' 

16.8 
13.3 
50.3 

.792 

116.7 
27.2 
70.5' 
14.3' 

18. 
19.5 
53.4 

1.088 

36.7$ 

147.3 
13. 
82.7' 
—8.2' 

73.6 
46.5 
59.9 

.632 

161.8 

27.5 
87.7' 
14.5' 

88.6 
74.4 
70.5 

.840 
32.9$ 

Suction  pressure            . 

Condenser  temperature  

Suction  temperature 

Horse  power   (indicated  of  steam 
cylinder)  

Kef  rigeration  (tons  per  24  hours)  
M:  E.  P  in  compressor 

Refrigerating    capacity   per   horse 
power  (tons  per  24  hours)  
Economy  of  high  over  low  evaporat- 

APPENDIX  I. 


349 


MEAN  EFFECTIVE  PRESSURE  OF  DIAGRAM 
OF  STEAM  CYLINDER. 


The  M.  E.  P.  for  any  initial  pressure  not  given  in  the  table  can  be  found 
by  multiplying  the  (absolute)  given  pressure  by  the  M.E.P.  per  pound 
of  initial,  as  given  in  the  third  horizontal  line  of  the  table. 


NOTE.— This  table  is  reprinted  from  "  Indicating  the  Refriger- 
ating Machine,"  publish«a  by  H,  S.  Rich  &  Co.,  Chicago. 


350 


MECHANICAL  REFRIGERATION. 


RELATIVE  EFFICIENCY  OF  FUELS. 

One  cord  of  air  dried  hickory  or  hard  maple  weighs  about  4,500 
pounds  and  is  equal  to  about  2,000  pounds  of  coal. 

One  cord  of  air  dried  white  oak  weighs  about  3,850  pounds  and 
is  equal  to  about  1,715  pounds  of  coal. 

One  cord  of  air  dried  beech,  red  oak  or  black  oak  weighs  about 
3,250  pounds  and  is  equal  to  about  1,450  pounds  of  coal. 

One  cord  of  air  dried  poplar  (white wood),  chestnut  or  elm 
weighs  about  2,350  pounds,  and  is  equal  to  about  1,050  pounds  of 
coal. 

One  cord  of  air  dried  average  pine  w< 
and  is  equal  to  about  625  pounds  of  coal. 

From  the  above  it  is  safe  to  assume  that  two  and  one-quarter 
pounds  of  dry  wood  is  equal  to  one  pound  average  quality  of  soft 
coal,  and  that  the  full  value  of  the  same  weight  of  different  wood 
is  very  nearly  the  same.  That  is,  a  pound  of  hickory  is  worth  no 
more  for  fuel  than  a  pound  of  pine,  assuming  both  to  be  dry.  It  is 
important  that  the  wood  be  dry,  as  each  10  per  cent  of  water  or 
moisture  in  wood  will  detract  about  12  per  cent  from  its  value  as 

TABLE  SHOWING  TENSION  OF  WATER  VAPOR  AT  DIFFERENT 
TEMPERATURES  IN  ABSOLUTE  PRESSURE,  AND  CORRESPOND- 
ING VACUUM  IN  INCHES  OF  MERCURY. 


jhs  about  2,000  pounds, 


Temperature. 
Deg;  F. 

Absolute  Pressure. 

Vacuum, 
Inches. 

Atmospheres. 

Inch  of  Mercury. 

212 

1. 

30. 

o. 

158 

0,307 

9.270 

•20.730 

140 

0.196 

5.880 

24.120 

122 

0.121 

3.630 

26.370 

113 

0,094 

2.820 

27.180 

104 

0.0722 

2.166 

27.834 

95 

0.0550 

1.650 

28.350 

86 

0.0415 

1.245 

28.755 

77 

0.0310 

0.930 

29.070 

68 

0.0229 

0.687 

29.313 

59 

0.0167 

0.501 

29.499 

50 

0.0121 

0.363 

29.637 

41 

0.0086 

0.258 

29.742 

32 

0.0061 

0.183 

29.817 

14 

0.0026 

0.078 

29.922 

—4 

0.0012 

0.036 

29.  964 

BOILING  POINTS  UNDER  ATMOSPHERIC  PRESSURE. 


Liquids. 

Fahr. 
deg. 

Cent, 
deg. 

Liquids. 

Fahr. 
deg. 

Cent, 
deg. 

Wrought  iron  (?) 

5000 

2760 

Alcohol  

173 

78 

Cast  iron  (?)     .... 

3300 

1815 

Ether  

96 

35 

Mercury  

675 

352 

Carbon,  bi-sulphurated.  . 

116 

47 

Whale  oil 

630 

332 

Water,  'distilled.. 

212 

100 

Oil  of  linseed  .... 
Oil  of   turpentine 
Sulphuric  acid.  .  . 

600 
357 
593 
570 

316 
180 
312 
300 

Salt,  sea  water.... 
Water,  20%  salt... 
Water,  30#  salt... 
Water,  40$  saturated 

213 

218 
222 
227 

101 

103 
105 
108 

Phosphorus  
Sweet  oil 

557 
412 

292 
211 

Ammonia,  liquid. 
Water,  in  vacuo  . 

140 

98 

60 
36 

Naphtha    

320 

160 

Chimogene  

+38 

33 

Nitric  acid 

220 

104 

Carbonic  acid.  .  .  . 

-112 

-80 

Milk  of  cows 

213 

101 

Ammonia  

—30 

—34 

Petroleum,  rectified 

316 

158 

Benzine  

187 

86 

APPENDIX  I. 


351 


COMPOSITION  OF  COMMON  WATER 

Chloride  of  sodium  contains Na 

Chloride  of  magnesium  contains... Mg 

Chloride  of  calcium  contains Ca 

Chloride  of  potassium  contains  — K 

Carbonate  of  soda  contains Na  O 

Carbonate  of  magnesia  contains.  ..Mg  O 

Carbonate  of  lime  contains Ca  O 

Carbonate  of  potassa  contains K  O 

Sulphate  of  soda  contains Na  O 

Sulphate  of  magnesia  contains  ....MgO 

Sulphate  of  lime  contains Ca  O 

Sulphate  of  potassa  contains K  O 


CONSTITUENTS. 

39.3  and  Cl      60.6 
26.28  and  Cl      74.73 
36.06  and  Cl      63.94 
52.45  and  Cl      47.55 
58.5   and  CO2  41.5 
47.62  and  C  Oa  52.38 
56.0   and  C  O,  44.0 
68.17  and  C  O2  31.83 
43.66  and  SO3  56.34 
33.33  and  SO3  66.67 
41.18andSO3  58.82 
54.08  and  S  O3  45.92 


Carbonate  of  lime  multiplied  by  0.56=lime. 

Sulphate  of  baryta  multiplied  by  0.343=sulphuric  acid. 

Phosphate  of  magnesia  multiplied  by  0.036=magnesia. 

Magnesia  multiplied  by  0.6=magnesium. 

Magnesium  multiplied  by  1.66=magnesia. 

Cubic  centimeter  carbonic  acid  multiplied  by  0.003=carbonic  acid 

C.  0.  mtrate  of  silver  solution  multiplied  by  0.0035=chlorlne  in 

grams. 

Chloride  of  sodium  multiplied  by  0.39=sodium. 
Carbonate  of  soda  multiplied  by  0.58=soda. 
Chloride  of  potassium  and  platinum  multiplied  by  0.16=potas»ium. 

In  the  construction  of  water  analysis  from  constituents  it  Is 
advisable,  as  most  consistent  with  practical  requirements  to  com- 
bine chlorine  with  magnesium  (balance  of  chlorine  with  sodium  or 
balance  of  magnesia  with  sulphuric  acid). 

Carbonic  acid  combines  with  lime,  balance  of  lime  with  sul- 
phuric acid,  balance  of  sulphuric  acid  with  soda  (or  balance  of 
carbonic  acid  with  magnesia). 

When  alkaline  carbonates  are  present  all  the  chlorine  is  to  be 
combined  with  sodium,  Magnesium  carbonate  and  calcium  sul- 
phate are  supposed  not  to  coexist. 


MILLIGRAMS  PER  LITER  TO 
GRAINS  PER  U.  6.  GALLON. 


GRAINS  PER  U.  S.  GALLON  TO 
MILLIGRAMS  PER  LITER. 


Milligrams 
per  Liter. 

Grains  per 
D.  S.  Gal. 

Milligrams 
per  Liter. 

Grains  per 
D.  S.  Gal. 

Grains  per 
U.  S.  Gal. 

lilligrams 
per  Liter. 

Grains  per 
U.S.  Gal. 

Milligrams 
per  Liter. 

1 

0.058 

26 

1.519 

1 

17.1 

16 

444.9 

2 

0.117 

27 

1.578 

2 

34.2 

27 

462.0 

3 

0.175 

28 

1.636 

3 

51.3 

28 

479.1 

4 

0.234 

29 

1.695 

4 

68.4 

29 

496.2 

5 

0.292 

30 

1.753 

5 

85.6 

30 

513.4 

6 

0.351 

31 

1.S12 

6 

102.7 

31 

630.5 

7 

0.409 

32 

1.870 

7 

119.8 

32 

547.6 

8 

0.468 

S3 

1.929 

8 

136.9 

83 

664.7 

9 

0.626 

34 

1.987 

9 

154.0 

84 

581.8 

10 

0.584 

35 

2.045 

10 

171.1 

85 

598.9 

11 

0.643 

36 

2.104 

11 

168.2 

36 

616.0 

12 

0.701 

37 

2.162 

12 

205.3 

87 

633.1 

13 

0.760 

38 

2.221 

13 

222.5 

38 

650.3 

14 

0.818 

39 

2.279 

14 

239.6 

89 

667.4 

15 

0.877 

40 

2.338 

15 

256.7 

40 

684.5 

16 

0.935 

41 

2.396 

16 

273.8 

41 

701.6 

17 

0.993 

42 

2.454 

17 

290.9 

42 

718.7 

18 

1.052 

43 

2.513 

18 

308.0 

43 

735.8 

19 

1.110 

44 

2.571 

19 

325.1 

44 

762.9 

20 

1.169 

45 

2.630 

20 

343.2 

45 

770.0 

21 

1.227 

46 

2.688 

21 

359.4 

46 

787.8 

22 

1.286 

47 

2.747 

22 

376.5 

47 

604.S 

23 

1.344 

48 

2.805 

23 

393.6 

48 

8S1.4 

24 

1.403 

49 

2.864 

24 

410.7 

49 

838.5 

25 

1.461 

50 

2.928 

25 

427.8 

50 

856.0 

352 


MECHANICAL  REFRIGERATION. 


EXPERIMENTS  IN  WORT   COOLING. 

The  following  tabulated  experiments  of  the  per- 
formance of  a  tubular  refrigerator  for  wort  cooling  are 
gleaned  from  Engineering.  The  water  and  wort  are 
moved  in  opposite  directions,  the  former  through  thin 
metallic  tubes,  which  are  surrounded  by  the  wort  to  be 
cooled: 


WORT. 

WATER. 

bo 

>> 

o> 

ed 

cj 

, 

w 

«s 

i 
rJ 

i|| 

g 

O 

0 

If? 
*£* 

& 

BO; 
&$ 

Is 

s 

•a 

«    ^ 

s, 

gi; 

& 

eg 

& 

•o 

E 

E^BJ 

<a 

^Sja  £ 
fl^iv 

1 

- 

0 

c^^ 

rt        ' 

- 

rt 

<J 

£ 

CO 

OJ        * 

3 

1 

c 

s 

c^ 

3 

e 

H 

c 

& 

Sq.  Feet. 

Bbls. 

Fahr 

Fahr 

Fahr 

Bbls. 

Fahr 

Fahr 

Fahr 

1      881 

33.9 

212° 

72° 

140° 

61  1 

65° 

169° 

104° 

2.    514 

1.104 

36.1 

•   155 

59 

96 

75  5 

54 

100 

46 

3.    514 

I  188 

36.6 

191 

59 

132 

9y.5 

54 

100 

46 

4.    514 

1.035 

47.3 

193 

59 

134 

90.7 

54 

100 

46 

5.     514 

1.018 

48.0 

178 

59 

119 

102.0 

54 

100 

46 

NOTE!.— A  barrel  contains  thirty-six  gallons,  or  360  pounds 
of  water. 

2.— The  temperature  of  the  air  in  Nos.  2  and  4  was  44°  F. 
and  in  Nos.  3  and  5, 40°. 


DIMENSIONS  OF  EXTRA  STRONG  PIPE. 


| 

2 

s 

a 

£o« 

ft§ 

i 

a 

« 

i 

1 

£^ 

t 

£ 

£O 

fa 

I-1  h 

SS 

Cfl 

Sn' 

5  . 

o^ 

<H 

o|° 

t~a 

'<**! 

<-"  a» 

(fi 

8 

C3  0 

O^frt 

*^j 

o3 

•i-l 

j3 

ad 

11 

!2J 

Actual 
Diam 

Actual 
Diam 

Thickn 

Sg 

Is 

Extern 
feren 

HJ 

Intern* 

Extern 

111 

Sou 

P 

In. 

In. 

In. 

In. 

In. 

In. 

Ft. 

In. 

In. 

Ft. 

Lbs. 

54 

0.205 

0.465 

0.100 

0.644 

1.461 

8.21 

0.0329 

0.1694 

4377 

0.29 

M 

0.294 

0.54 

0.123 

0.924 

1.697 

7,07 

0.0678 

0.2290 

2124 

0.54 

0.421 

0.675 

0.127 

1.323 

2.121 

5.66 

0.1394 

0.3573 

1033 

0.74 

H 

0.542 

0.84 

0.149 

1.703 

2.639 

4A5 

0.2307 

0.6542 

624.2 

1.09 

0.736 

1.05 

0.157 

2.312 

3.299 

3.67 

0.4254 

0.8659 

338.7 

1.39 

1 

0  951 

1.315 

0.182 

2.988 

4.131 

2.90 

O'.TIOS 

1.3582 

202.7 

2.17 

1/4 

1.272 

1.66 

0.194 

3.990 

5.215 

3.30 

1.2707 

2.1642 

113.3 

3.00 

1% 

1.494 

1.90 

0.203 

4.695 

5.969 

2.01 

1.7530 

2.8353 

82.15 

3.63 

2 

1.933 

2.376 

0.221 

6.075 

7.  461 

1.61 

2.9345 

4.4302 

49.72 

5.02 

24 

2.315 

2.875 

0.280 

7.304 

9.032 

1.33 

4.1989 

6.4918 

34.28 

7.67 

3 

2.892 

3.5 

0.304 

9.085 

10.996 

1.09 

6.5688 

9.6211 

21.91 

10.25 

3H 

3.358 

4.0 

0.321 

10.550 

12.566 

0.931 

8.  7561 

12.5664 

16.23 

12.47 

4 

8.818 

4.5 

0.341 

LI.  995 

14.137 

0.849 

11.4608 

15.9043 

12.56 

14.97 

5 

4.813 

5.563 

0.375 

15.121 

17.477 

0.687 

18.193 

24.3010 

7.915 

20.54 

6 

5.750 

6.625 

0.437 

18.064 

20.813 

0.576 

25.967 

34.4496 

5.542 

28.58 

APPENDIX  II.  353 

APPENDIX  II.—  PRACTICAL  EXAMPLES. 


INTRODUCTORY  REMARKS. 

The  following  practical  examples,  problems  and  ques- 
tions have  been  discussed  for  a  two-fold  purpose.  In  the 
first  place  their  object  is  to  give  to  those  not  accustomed 
to  the  use  of  books  an  idea  as  to  how  the  Compend  may  be 
utilized,  and  to  show  them  in  particular  that  the  formulas 
may  be  referred  to  by  any  man  of  ordinary  acquaintance 
with  the  rules  of  common  arithmetic;  and  to  also  show 
them  how  most  questions  can  be  answered  without  the 
use  of  such  formulae,  by  referring  to  more  convenient 
rules  or  tables  in  the  book  or  appendix  of  tables. 

In  the  second  place  these  problems  are  calculated  to 
answer  such  questions  as  frequently  occur  in  the  refrig- 
erating practice,  and  to  discuss  certain  questions  in  a 
more  direct  way  than  it  was  practicable  to  do  in  the  body 
of  the  book. 

By  carrying  out  the  formulae  in  numerical  quantities 
in  this  appendix  it  was  also  intended  to  please  those 
who  profess  a  great  preference  in  favor  of  formulae  writ- 
ten altogether  in  figures,  and  not  with  figures  and  letters 
of  the  alphabet  mixed.  It  is  also  probable  that  by 
studying  the  solutions  in  this  appendix  more  carefully 
they  will  discover  the  reasons  why  formulae  are  thus 
written,  viz. :  In  order  to  make  the  necessary  distinction 
between  constant  numerical  quantities  which  never 
change,  and  which  therefore  are  given  their  constant 
numerical  value  in  the  formula  and  between  the  quanti- 
ties which  change  with  every  example  and  which  there- 
fore are  given  in  letters  of  the  alphabet,  for  which  the 
different  values  are  to  be  inserted  in  every  different 
example. 

FORTIFYING  AMMONIA  CHARGE. 

Q.— How  many  pounds  (a;)  anhydrous  ammonia 
should  be  added  to  600  pounds  of  ammonia  liquor  in 
absorption  machine  showing  20°  Reaume  (scale  show- 
ing 10°  in  pure  water)  to  make  it  26°  Beaume"  ? 

From  table  on  page  97  we  find  20°  Beaume  to  corre- 
spond to  17  per  cent,  and  26°  Beaume  to  correspond  to 
about  28  per  cent  of  ammonia;  hence  in  formula  on  page 
285,  ra  is  equal  to  600,  a  =  20,  b  =  28,  and  therefore  x  = 
600  (28  —  20)  600  X  8 

100  -  28     =  ~~72~   =  66'6  P°unds- 


354  MECHANICAL  REFRIGERATION. 

EXAMPLES   ON  SPECIFIC  HEAT. 

QUESTION.—  What  amount  of  heat  must  be  abstracted 
from  1,000  pounds  of  beer  wort  of  14  per  cent  to  reduce 
its  temperature  from  70  to  40°  F.  ? 

Specific  heat  c  of  wort  from  page  158  =  0.902  =»  0.9, 
according  to  page  16:  S=*  c  X  t  X  w  =  0.9  X  (70—40)  X 
1000  =  0.9  X  30  X  1000  =  27000  units. 

Q.—  What  will  be  the  final  temperature  T,if  1,000 
pounds  of  beer  wort  of  14  per  cent  and  of  a  temperature 
of  180°  degrees  are  mixed  with  1,200  pounds  of  water  of 
6(P  F.? 

In  accordance  with  page  17  we  find  — 


1200  x  60  X  1  +  1000  X  180  X  (X9 


W  fi  +  to,  st  1200  X  1  X1000  X  0.9 


„, 

' 


EVAPORATIVE  POWER  OP  COAL. 

Q.—  If  a  lignite  contains  60  percent  of  carbon  (C)  and 
5  per  cent  of  hydrogen  (H),  what  will  be  its  evaporative 
power  (e)  expressed  in  pounds  of  water? 

From  page  37  we  find— 
e  «  .15  (G  +  4.29  H)  =  0.15  (60  +  5  X  4.29)  =•  12.21  pounds. 

CAPACITY  OF  FREEZING  MIXTURE. 

Q.—  How  many  pounds  of  ammonia  nitrate  must  be 
dissolved  in  so  many  pounds  of  water  to  obtain  a  theoreti- 
cal refrigerating  effect  equal  to  one  ton  ice  melting 
capacity  =  284,000  units? 

On  page  32  we  find  that  1  pound  will  reduce  the  tem- 
perature from  40°  to  4°,  which  is  equivalent  to  a  refrigerat- 
ing effect  of  2  x  (40-4)  =  72  units  if  we  assume  the  spe- 
cific heat  of  the  solution  equal  to  that  of  water  =  1.  Hence 
isAQOfi  _  about  4,000  pounds  of  the  salt  must  be  dissolved 
in  4,000  pounds  of  water  to  obtain  the  required  effect  the' 
oretically;  practically  it  would  take  a  great  deal  more. 

EXAMPLES  ON  PERMANENT  GASES. 

Q.—  If  the  volume  V  of  a  gas  is  ten  cubic  feet  at  a 
pressure  of  eighteen  atmospheres  and  a  temperature  of 
40°,  what  will  be  its  volume  Ft  if  expanded  to  a  pressure 
of  one  atmosphere  and  a  temperature  of  —  80°  ? 

Examples  of  this  kind  occur  quite  frequently,  and 
their  study  will  be  found  very  instructive  and  profitable. 


APPENDIX  II.  355 

The  formula  at  bottom  of  page  48  gives— 

18  (-8Q+46D  =  10  18X381 
i  (40+461)          J  1X501 
Q.— What  volume  x  in  cubic  feet  is  occupied  by  180 
cubic  feet  of  a  permanent  gas  if  its  temperature  is  reduced 
from4(Pto  —  80°  F.? 

According  to  page  55  the  volume  of  a  gas  is  propor- 
tional in  its  absolute  temperature.    Hence  we  have— 
180  :  x  =  (40  +  461)  :  (—80  +  461)  =  501 : 381 
or  x  =  m*™= 137  cubic  feet. 

EXAMPLES  SHOWING  USE  OF  GAS  EQUATION. 

Q. — What  will  be  the  pressure  of  a  confined  volume 
of  air  at  a  temperature  45°  if  its  pressure  at  32°  F.  is  equal 
to  one  atmosphere? 

According  to  the  equation  for  perfect  gases,  page  55,is: 

f       45  -4-  461 
P  V  ~  493  =  — 493 °r  V  remainin£  unit* 

CA£* 

p  =  — r  =  1.08  atmospheres  or  thereabouts. 
4y<~> 

Q. — What  will  be  the  volume  of  one  cubic  foot  of  air 
if  heated  at  constant  pressure  from  32°  to  45°  F.,  its  press- 
ure at  the  former  temperature  being  one  atmosphere? 

According  to  the  same  equation  we  find— 

T       45  -4-  461 
p  V  =  493  =      493    or  P  remaining  unit. 

KAf> 

v==  |^==1.03  cubic  feet. 

Q.— If  the  volume  of  a  confined  body  of  a  permanent 
gas  be  one  cubic  foot  at  the  temperature  of  32°  and  at  a 
pressure  of  one  atmosphere,  what  will  have  to  be  its  tem- 
perature T  in  order  that  it  may  occupy  a  volume  of  one- 
half  cubic  foot  at  a  pressure  of  four  atmospheres? 

The  same  equation  answers  the  question,  viz. : 

p  v  =  ^  or  T=493p v  =  493X4XM  =  986°  F.  absolute. 
01986  — 461  =  525°  F. 

WORK  REQUIRED  TO  LIFT  HEAT. 

Q.— What  amount  of  work  must  be  expended  theo- 
retically by  a  perfect  refrigerating  machine  to  withdraw 
284,000  units  of  heat  (one  ton  refrigeration)  from  a  refrig- 


356  MECHANICAL  REFRIGERATION. 

erator  at  temperature  of  10°  if  the  temperature  in  the 
condenser  is  90°  ? 

Prom  the  equation,  page  71, 

5  =   mT    „     we  find— 
W       Tt-T0 


The  work  is  aere  expressed  in  heat  units,  which  are 
equivalent  to: 

49,000  X  772  =  37,830,000  foot-pounds  (page  346)  or  to 

=0'8-horse  P°™r*-**(page  346). 


REFRIGERATING  EFFECT  OF  SULPHUROUS  AGED. 

Q.—  What  is  the  theoretical  refrigerating  effect  r  of 
one  pound  and  of  one  cubic  foot  of  sulphurous  acid  if 
used  in  a  compression  machine,  the  temperature  in  re- 
frigerator coils  being  5°  and  in  condenser  coils  95°  F.? 

The  equation  r  =  h^  —  (t  —  tt)st  on  page  115,  applies 
also  for  sulphurous  acid,  for  which  we  find  fit  =  171  units 
(page  250)  and  s  =  0.41  (page  250)  ;  hence— 

r  =  161  —  (95  —  5)  0.41  161—37  =  124  units. 

From  same  table  we  find  the  weight  of  one  cubic  foot 
of  sulphurous  acid  at  5°  equal  to  0.153  pounds;  hence  the 
refrigeration  of  one  cubic  foot  is  — 

124X0.153  =  18.97  units. 

REFRIGERATING  CAPACITY  OF  A  COMPRESSOR. 

Q.  What  is  the  refrigerating  capacity  of  a  double- 
acting  compressor,  70  revolutions  per  minute,  diameter 
9^  inches  and  stroke  16^£  inches,  temperature  in  re- 
frigerator coil  5°  and  in  condenser  coil  85°  F.? 

The  compressor  volume  C  per  minute  after  formula 
on  page  303  is— 

C=dz  X  I  X  m  X  0.785  =  9^2  X  16^  X  0.785  X  70. 
From  table  on  page  250  we  find  9^2  X  0.785  =  76.58. 

Hence  G  =  76.58  X  16.5  X  70  =  88410  cubic  inches. 

The  compressor  being  double-acting,  this  is  equal  to 


From  table  on  page  125  we  find  that  3.34  cubic  feet  of 
ammonia  must  be  pumped  per  minute,  at  above  named 
condenser  and  compressor  temperature  to  produce  a 
refrigerating  effect  of  one  ton  in  twenty-four  hours,  hence 


APPENDIX  II.  357 

the  above  compressor  represents  a  theoretical  refrigerat- 
ing efficiency  of— 

15i=  30.5  tons. 
3.34 

SECOND  METHOD  OF  CALCULATION. 

The  actual  refrigeration  will  be  from  15  to  20  pei 
cent  less,  or  equivalent  to  about  25  tons  (commercial 
capacity  ?);  see  table  page  302,  according  to  which  the 
nominal  daily  refrigerating  capacity  is  — 


_=  25.5  tons. 
4  4 

The  agreement  between  this  amount  and  the  amount 
found  by  the  first  calculation  holds  good  only  for  the 
temperature  selected;  otherwise  the  last  rule  affords  only 
a  crude  approximation. 

THIRD  METHOD  OF  CALCULATION. 

The  theoretical  refrigerating  effect  E  of  this  com- 
pressor can  also  be  calculated  after  the  formula  on  page 

118— 

E  =  C  X  60  X  r 

We  find,  according  to  formula  on  page  115  and  table 
on  page  94,r  =  h,  —  (t  —tt  )  s  =  552.43  —  (  85  —5)  1  =  552-80 
=  472  units,  and  v  =8.06  (page  94)— 

109  V  fiO  V  4.79 

E  =       ofi     -  units  or  in  tons  per  dav- 


_  102X60X472X24 

8  X  284.000.  '0nS< 

Or,  again,  the  actual  refrigerating  capacity  will  be 
about  15  to  20  per  cent  less,  or  equivalent  to  about  twenty- 
five  tons,  and  the  actual  ice  making  capacity  will  be  about 
thirteen  tons  per  twenty-four  hours.  The  last  method 
of  calculation  will  answer  also  for  other  refrigerating 
media  if  r  and  v  are  found  and  inserted  accordingly. 

COOLING  WORT. 

Q.—  A  direct  expansion  ammonia  refrigerating  ma- 
chine is  applied  to  the  cooling  of  beer  wort,  and  reduces 
the  temperature  of  300  barrels  of  wort  from  70°  to  40°  F. 
in  four  hours.  What  is  the  refrigerating  capacity  U  of 
the  machine  if  the  weight  of  the  wort  is  14°  Balling? 

From  table  on  page  202  we  find  the  specific  gravity 
corresponding  to  14°  equal  to  1.0572  (1.06),  and  from  table 


358  MECHANICAL  REFRIGERATION. 

on  page  197  we  find  the  specific  heat  0.895  (0.9),  hence  in 
accordance  with  formula  on  page  198— 

U  B  X  259  X  g  X  s  (70  —  40)     300  X  259  X  1.06  X  0.9 

X  30   222300  units. 

This  is  the  refrigeration  in  three  hours;  expressed  for 
twenty-four  hours,  and  in  tons  of  refrigeration,  it  is 
equal  to— 

about  60  ton, 

The  actual  refrigeration  required  to  cool  the  wort  is 
only  one-eighth  of  that  (for  three  hours),  i.  e.,  1%  tons, 
which  is  about  one  ton  for  every  forty  barrels.  The  rule 
on  page  199  allows  one  ton  for  every  thirty-eight  barrels. 

HEAT  BY  ABSORPTION  OF  AMMONIA. 

Q.— What  is  the  heat  Hn  developed  when  one  pound 
of  ammonia  vapor  is  absorbed  by  enough  of  a  20  per  cent 
solution  of  ammonia  in  order  to  produce  a  33  per  cent 
solution  of  ammonia  ? 

On  page  226  we  find— 

a      925_  248X1426   =unlta- 
n 

In  accordance  with  the  definitions  given  on  page  226 
we  find  n,  that  is  the  number  of  pounds  of  water  present 
to  one  pound  of  ammonia  in  a  20  per  cent  solution,  = 

80 

yz  =  4,  and  the  number  of  pounds  of  ammonia  (6  + 1 

pounds)  which  are  present  for  every  four  pounds  of  water 

4  X  33 
in  a  33  per  cent  solution        -^ 2  pounds. 

6  +  1  being  =  2,  it  follows  6  =  1. 
We  now  insert  these  values  in  the  above  equation  for 

a-WS-^i^i      819  units. 

RICH  LIQUOR  TO  BE  CIRCULATED. 

Q.— How  many  pounds  P2  of  rich  liquor  of  33  per  cent 
strength  must /be  circulated  in  an  ammonia  absorption 
plant  if  the  poor  liquor  enters  the  absorber  at  20  per  cent 
strength  ? 

We  find  this  in  accordance  with  equation  on  page  224: 

_          (100  — a)    100  (100  —  20)100 

**  ~~  (100  —  a)  c  —  ( 100  —  c)  a  =  (100  —  20)  33  —  (100  —  33)  20 
8000 

=  Poo  =  6.1  pounds. 


APPENDIX  II.  359 

CAPACITY  OF  ABSORPTION  MACHINE. 

Q._\Vhat  should  be  the  theoretical  refrigerating 
capacity  R  of  an  ammonia  absorption  machine  if  the 
rich  liquor  is  33  per  cent  and  the  poor  liquor  20  per 
cent  strong,  and  if  the  ammonia  pump  makes  fifty 
revolutions  per  minute  and  each  stroke  is  seven  inches 
and  the  diameter  of  pump  piston  three  inches? 

From  page  139  we  find  the  capacity  C  of  this  pump 
to  be  2.14  gallons  at  ten  strokes  per  minute,  hence  at 
fifty  strokes  it  is  expressed  in  pounds  — 

C  =  2.14  x  5  X  8.3  =  90  pounds  in  round  figures. 

By  calculating  as  before  from  table  on  page  226 
we  find  P2  =  6.1,  and  according  to  formula  on  page  230 
we  find  — 

X         90X453 


-£*2  O.-L 

The  value  for  r  is  found  after  the  rule  on  page  185, 
which,assuming  the  temperature  in  refrigerator  coils  to  be 
4°  and  the  pressure  in  condenser  to  210  pounds,  equiva- 
lent to  an  absolute  pressure  of  225  pounds  and  to  a  tem- 
perature of  104°  F.  (see  table  on  page  94),  reads— 

r  =  /ix  —  (t—tt)  s  =  553  —  (104—  4)  1  =  453  units. 
hj  =  553  units  from  table  on  page  94. 

One  ton  of  refrigerating  capacity  per  day  being  equal 
to  284000  units,  one  ton  per  hour  is  equal  to  about  12000 
units,  and  one  ton  of  refrigerating  capacity  per  minute 
is  equivalent  to  200  units  per  minute,  and  therefore  the 
above  refrigeration  is  equivalent  to  — 

=  33.5  tons  per  day  (theoretical  capacity). 


If  we  allow  25  per  cent  for  losses  all  around  slips  of 
pumps,  radiation,  etc.,  we  find  the  actual  refrigerating 
capacity  33.5  —  8.4  =  25.1  tons,  and  the  actual  ice  making 
capacity  being  about  half  of  that  =  twelve  tons  per  day. 

HEAT  AND  STEAM  REQUIRED. 

What  is  the  theoretical  amount  of  heat  TFi  and  of 
steam  P5  required  in  still  of  above  plant  ? 
From  page  192  we  find— 

Wi  =  Hn  —  (h2—fi)  =  819  —  (495—489)  =  813  units, 
h2  at  a  temperature  of  90°  in  absorber  being  495  units, 
h  and  at  a  temperature  of  104°  in  condenser  being  489 


360  MECHANICAL  REFRIGERATION. 

units,  after  table  on  page  92.    H    819,  from  table  on 

page  226.    The  amount  of  steam  P5  in  pounds  required 

per  hour  to  run  this  plant  would  be  (see  page  229): 

p         TV*  X  m  X  28400      813  X  25  X  284000      77Q 

24  X  r  X  hB  24  X  453  X  686 

pounds  of  steam  per  hour. 

hB  =  886  (at  pressure  in  boiler  100  absolute  or  85  pounds 
gauge  pressure).  To  this  should  be  added  about  £  to 
allow  for  steam  to  run  the  ammonia  pump,  so  that  the 
whole  would  amount  to  about  900  pounds  per  hour. 

COLD  STORAGE  EXAMPLES. 

Q.—  What  is  the  refrigeration  E  required  for  a  local 
storage  room  40X50X10  if  each  day  about  30,000  pounds 
of  fresh  meat  (about  120  hogs)  are  placed  in  the  same  at 
a  temperature  of  95°  to  be  envied  to  a  temperature  of 
35,  if  the  temperature  of  atmosphere  is  to  be  85°  P.? 

METHOD  OF  CALCULATION. 

The  side  walls  of  room  2x50x10+2x40X10=1,800  sq.ft. 
The  ceiling  and  floors  2  X  40  X  50  =4,000  " 

Total  ............................  5,800  sq.ft. 

If  we  take  n  as  3  all  around  (assuming  an  average  de- 
gree of  insulation  (see  page  181),  we  have— 


frigeration  per  day  to  keep  the  room  at  the  desired 
temperature. 

The  additional  refrigeration  to  chill  the  meat,  assum- 
ing its  specific  heat  to  be  0.8,  we  find  (page  183)— 

P(£—  £t)      30000(95  —  35)   = 
^~  355000      ""        355000  tons» 

which  makes  a  total  refrigeration  of  8.1  tons  required. 
For  closer  estimates  the  rules  on  pages  181  and  182 
may  be  used. 

APPROXIMATE   ESTIMATE. 

The  cubic  contents  of  the  room  are  equal  to  20,000 
cubic  feet,  and  in  accordance  with  the  rules  on  page  173 
from  fifty  to  100  units  (say  seventy-five  units  in  this  case) 
are  allowed  per  cubic  foot,  and  in  addition  to  that  about 
50  per  cent  more  for  chilling,  which  amounts  to  about  110 
units  in  all  per  cubic  feet,  or  a  daily  refrigeration  of 

r°Und 


APPENDIX  II.  361 

For  opening  doors,  for  windows,  etc.,  about  10  to  15 
per  cent  extra  refrigeration  may  be  allowed,  making  the 
total  about  nine  tons  refrigerating  capacity  per  day. 
See  also  rules  on  page  212  and  213. 

PIPING  REQUIRED. 

Q.—  What  will  be  the  amount  of  2-inch  pipe  direct 
circulation  required  for  the  above  room  and  purpose? 

In  accordance  with  rule  on  page  128  we  assume  that 
one  square  foot  of  pipe  will  convey  about  2,500  units  of 
refrigeration;  this  is  equal  to  1.6  foot  of  2-inch  pipe  (table 
on  page  129),  hence  to  distribute  nine  tons  in  twenty-four 
hours  the  pipe  required  will  be— 

9  X  284000  X  1.6  =160Q  ^  Qf  ^^  pjpe_ 


According  to  another  rule,  given  on  page  212,  one 
running  foot  of  2-inch  pipe  is  allowed  for  thirteen  cubic 
feet  chilling  room  capacity,  in  accordance  with  which 

9Q   QQQ 

^  \      =  1,540  feet  or  thereabouts  of  2-inch  pipe  would 

lo 

be  required. 

After  still  another  rule,  given  on  page  212,  we  find  that 
six  feet  2-inch  pipe  are  allowed  per  hog  slaughtered  in 
chilling  room;  according  to  this  rule  we  would  only  re- 
quire 720  feet  of  2-inch  pipe  for  above  room,  but  the  rule 
from  which  this  result  is  obtained  applies  to  large  instal- 
lations having  over  a  hundred  times  the  capacity  contem- 
plated in  the  example  as  given  and  calculated  above. 

EXAMPLES  ON  NATURAL  GAS. 

Q.—  What  amount  of  refrigeration  and  work  can 
be  produced  by  natural  gas  expanding  adiabatically 
from  a  pressure  of  255  pounds  (seventeen  atmospheres) 
to  a  pressure  of  fifteen  pounds  (one  atmosphere)  absolute 
pressure,  and  to  a  volume  of  1,000,000  cubic  feet  at  the 
ordinary  temperature  and  pressure? 

TEMPERATURE  AFTER  EXPANSION. 

If  we  assume  the  initial  temperature  of  the  gas  to  be 
70°  ==  70  +  461  =  531°  absolute  we  find  the  temperature 
jP2  of  the  gas  after  expansion  after  the  rule  on  page  257, 
viz: 

fc—  1  .1.41  —  1  0.291 

or 


362  MECHANICAL  REFRIGERATION. 

log.  Tt  =  log.  531  X  0.291  (log.  1-  log.  17)  —  2.7251-0.6432 

=  2.0819. 

rz  =  num.  log.  2.0819  =  121°  absolute  =  461  —  121  =  — 
34(PF. 

REFRIGERATING  CAPACITY. 

^The  theoretical  refrigeration  H  produced  by  1,000,000 
cubic  feet  expanded  in  this  manner  if  the  gas  leaves  the 
refrigerator  at  the  temperature  T0  of  5°  =  466°  absolute 
is  found  after  the  formula  on  page  257. 

H—  mkc  (T0  —  T2]  =•  mfcc(466  —  121) 

c=-  0.468  (page  47) 

w=»  0.0316  pounds  (page  233  coal  gas)  hence 

H=  0.0316X0.468X1.41X345  =  7.0  units  per  cubic 
foot  or  7,000,000  units  per  1,000,000  cubic  feet,  which  is 
equivalent  to  a  theoretical  refrigerating  capacity  of 
about  twenty-five  tons.  The  actual  ice  making  capacity 
would  probably  be  less  than  ten  tons  per  day. 

WORK  DONE  BY   EXPANSION. 

The  amount  of  work,  Wm,  that  can  be  obtained 
theoretically  by  the  adiabatic  expansion  to  1,000,000 
cubic  feet  of  the  gas  is  expressed  by  the  formula— 


Wm  =          (T  —  T2]  =  0.0316  X  0.468  X  1.41  (531  -  121) 

X  772  —  about  6600  foot-pounds 
per  cubic  foot,  or  for  1,000,000  cubic  feet  per  day 

ab°Ut  147  h°rse  P0wers  per  day- 


According  to  this  calculation  the  power  to  be  gained 
would  be  of  considerably  more  consequence  than  the  ice, 
but  it  must  not  be  forgotten  that  these  are  theoretical 
calculations  which  are  naturally  greatly  reduced  in  prac- 
tical working,  not  to  speak  of  possible  difficulties  con- 
nected with  the  same. 

SIZE  OF  EXPANDING  ENGINE. 

As  the  expanded  gas  leaves  the  expanding  engine 
at  the  temperature  of  121°  absolute,  its  volume  x  is  less  in 
the  following  proportion— 

1000000  :  x  =  531  :  121  (page  55) 

228000  cubic  feet. 


APPENDIX  tt.  363 

This  is  the  volume  over  which  the  piston  of  expand- 
ing engine  must  sweep  in  one  day.  If  it  is  double-acting 
and  makes  fifty  revolutions  a  minute  the  size  of  the 
cylinder  must  be — 

6oirS3<60=m  =  1-6cublcfeet- 

If  the  stroke  be  two  feet  the  area  of  piston  must  be 
0.8  square  feet. 

EXPANSION  WITHOUT  DOING  WORK. 

Q.— What  amount  of  refrigeration  can  be  produced 
by  natural  gas  expanding  from  a  pressure  of  255  pounds, 
absolute,  to  a  volume  of  1,000,000  cubic  feet  at  the 
atmospheric  pressure  without  doing  work? 

REFRIGERATION  OBTAINABLE  BY  EXPANSION  ALONE. 

For  the  sake  of  simplicity  we  neglect  the  contraction 
of  the  gas  due  to  reduction  of  temperature,  and  allow  the 
theoretical  refrigeration  to  be  equivalent  to  the  external 
work,  JE?,  done  by  the  expanding  gas,  which  can  be  found 
by  the  formula  for  steam  on  page  106— 

P(V-V^) 


v  representing  the  final  volume  and  vt  the  original  volume 
of  the  expanding  gas,  and  calculated  for  one  cubic  foot; 
hence  — 


E  =          2"~  **  =  0.31  units  per  cubic  foot. 

or  310,000  units  for  1,000,000  cubic  feet  of  gas,  of  which 
only  a  fraction  could  be  utilized  for  ice  production,  which 
would  probably  be  less  than  one-third  ton  per  day. 

CALCULATION  OF  REFRIGERATING  DUTY. 

Q.  A  machine  is  required  to  cool  water  from  55°  F.  to 
40°  F.  during  part  of  the  day,  and  to  keep  a  cold  storage 
at  15°  F.  at  other  part  of  the  day.  What  indicated  horse 
power  steam  engine  will  be  required  to  work  compressors 
to  extract  3,000,000  B.  T.  U.  per  hour  from  the  water  at 
above  temperatures,  and  what  size  compressors,  with 
number  of  revolutions  per  minute  ?  What  B.  T.  U.  per 
hour  would  same  machine  extract  at  same  speed  when 
working  on  the  cold  storage,  and  what  would  then  be  its 
indicated  horse  power  ?  Condensing  water  at  60°  and  leav- 
ing condenser  at  70°  F. 


364  MECHANICAL  REFRIGEKATION. 

If  we  assume  that  you  work  by  direct  expansion,  the 
temperature  of  the  expanding  ammonia  would  have  to 
be  about  10°  lower  than  the  water  after  it  is  cooled,  i.  e., 
30°;  consequently  by  using  the  latent  heat  of  vaporiza- 
tion at  that  temperature,  as  we  find  it  in  table  on  page  94, 
viz.,  536,  and  formula  on  page  115  of  Compend  we  mid— 

•  r  =  536  —  (70—30)  1  =  496  units, 

which  is  the  refrigerating  effect  of  one  pound  of  ammonia, 
when  the  temperature  of  the  refrigerator  is  30°  and  that 
of  the  condenser  70°,  the  specific  heat  of  the  ammonia 
being  1. 

The  amount  of  ammonia  to  be  evaporated  per  minute 
is,  therefore— 


From  same  table  on  page  94,  we  find  volume  of  one 
pound  of  ammonia  vapor  at  30°  =<  4.75  cubic  feet,  con- 
sequently the  compressor  capacity  per  minute  will  have 
to  be— 

101  X  4.75  —  480  cubic  feet  in  round  numbers. 

If  we  add  to  this  20  per  cent  for  clearance  losses  by 
radiation,  etc.,  we  require  an  actual  compressor  capac- 
ity of  576  cubic  feet  per  minute.  If  we  assume  that  the 
work  is  to  be  done  by  one  double-acting  compressor, 
making,  say,  seventy  revolutions  per  minute,  we  require 
a  compressor  having  the  cubic  capacity  of— 
576 


72  X  2 


4.2  cubic  feet. 


If  we  distribute  this  capacity  over  two  compressor 
cylinders  each  one  has  to  have  a  volume  of  2.1  cubic  feet. 

Taking  the  diameter  of  each  of  them  at  fifteen  inches 
the  area  is  (1.252  X  0.785)  1.227  cubic  feet,  and  the  stroke 
will  have  to  be— 

-==  17.12  inches. 


If  we  start  from  a  different  given  stroke  and  num- 
ber of  revolutions,  as  we  probably  shall,  the  diameter 
changes  accordingly,  after  the  foregoing  simple  rule. 

If  a  single  double-acting  compressor  making  fifty 
revolutions  were  to  do  the  work,  its  dimensions,  calcu- 
lated on  the  same  basis  as  above,  would  be  twenty  inches 
diameter  by  31^  -inch  stroke. 


APPENDIX  II.  365 

The  work  of  the  compressor  is  found  after  the  for- 
mula on  page  119  : 

W=  0.0234  WK  horse  power; 

X  536X101=104 

horse  power. 

And  the  horse  power  of  engine,  after  rule  on  page  121 
of  Compend,  is  found  to  be— 

104X1.4=  145.6  horse  power. 

The  same  two  compressors,  if  required  to  do  duty  in 
a  cold  storage  plant,  would  probably  have  to  run  with  a 
temperature  of  5°  F.  in  refrigerator.  In  this  case  (their 
cubic  capacity  being  576  cubic  feet  per  minute)  their  re- 
frigerating capacity  in  tons  per  day  is  found  by  the  for- 
mula on  page  303  of  Compend,  viz.: 

B_£fc-H1)  =»:^t5)_212  ^  ln  round 

figures  (hj^  and  v  being  found  from  table  on  page  94).    Or 
in  thermal  units  per  hour— 

212  ^-^^  2500000  units. 

This  is  the  theoretical  capacity;  to  bring  it  on  a  prac- 
tical basis,  we  have  to  subtract  20  per  cent,  as  we  did  in 
the  case  of  water  cooling  before  this  yields  2500000—500000 
=  2000000  units  per  hour  actual  refrigerating  capacity  for 
cold  storage. 

To  find  the  horse  power  of  the  compressor  in  this 
case  we  find  the  amount  of  ammonia  to  be  circulated  in 
a  minute,  as  before,  viz.: 

r  =  546  —  (70  —15)  =  491,  and 
.~      2000000 


49TX60 

Placing  this  value  in  the  equation  from  page  119,  as 
before,  we  find— 

TF4=  0.0234  X   7^~5  X  546  X  68—118.7  horse  power; 

and  the  horse  power  of  engine- 

US.  7  X  1.4  =  166  horse  power. 

These  horse  power  are  calculated  from  the  amount  of 
ammonia  theoretically  required,  and  about  15  to  25  per 
cent  should  be  added  to  bring  them  within  practical 
range.  We  have  also  assumed  that  the  temperature  in 
condenser  is  that  of  outflowing  condenser  water,  when 
in  fact  it  should  be  taken  5°  higher. 


366  MECHANICAL  REFRIGERATION". 

CALCULATING  ICE  MAKING  CAPACITY. 

Q.  —  What  is  the  ice  making  capacity  of  two  single- 
acting  compressors  7x12  inches,  100  revolutions  per 
minute? 

The  capacity  in  cubic  feet,  (7,  for  each  compressor 
per  minute,  according  to  formula  on  page  117  of  Com- 
pend,  is— 

C=r2  X  3.145  X6xm 

7*  X  3.145  X  12  X  100     9ft  ,      ..    f 
-  -  =    —        —=26.7  cubic  feet, 


or  for  both  compressors,  26.7  x  2  =  53.4  cubic  feet,  which 
under  general  conditions,  when  no  back  pressure,  etc., 
is  mentioned,  has  been  calculated  to  be  equivalent  to 

~—      13.35  tons  of  refrigerating  capacity  in  twenty- 

four  hours  (see  page  118  of  Compend),  and  of  this  from 
iS  to  !%  is  available  actual  ice  making  capacity,  which 
accordingly  is  about  seven  tons  per  day  (more  or  less;  see 
page  144  of  Compend). 

VOLUME  OF  CARBONIC  ACID  GAS. 

Q.  —  What  is  the  volume  of  one  pound  of  carbonic 
acid  gas  at  a  pressure  of  thirty  pounds  and  at  a  tem- 
perature of  50°? 

The  formula  that  applies  here  is  given  on  page  48  of 
the  Compend,  viz.: 

Fp^  +  461) 


If  in  this  formula  we  insert  for  V  the  volume  of  one 
pound  of  carbonic  acid  gas  at  the  atmospheric  pressure, 
viz.,  8.5  cubic  feet,  and  forp  the  pressure  of  the  atmos- 
phere, viz.,  14.7  pounds,  and  for  t  the  temperature  of  32° 
F.  this  formula  becomes: 

V1  _  8.5(461  +  ^)14.7      115  +  0.25  <t 
493  pl  p± 

Hence  the  volume  F1  of  one  pound  of  carbonic  acid 
gas  at  any  given  temperature  and  pressure,  say  at  an  ab- 
solute pressure  of  thirty  pounds,  and  a  temperature  of 
50°,  is  found  by  inserting  these  quantities  in  the  fore- 
going formula: 

Trf      115  +  0.25X50        127.5        .  oe      ,. 

F1  --  ^~~w  ---  =  —  go—  =  4.  25  cubic  feet. 

For  apparent  reasons  the  numerical  results  of  above 
examples  have  been  rounded  off  in  most  cases. 


APPENDIX  II.  367 

HORSE  POWER  OP  STEAM  ENGINE. 

Q.— What  is  the  horse  power  of  a  steam  engine  the 
piston  of  which  has  a  diameter  of  12  inches,  a  stroke  of 
30  inches  at  90  revolutions  a  minute  if  the  gauge  pressure 
of  the  steam  is  80  pounds,  cut-off  £  ? 

To  calculate  the  horse  power  in  this  case  we  have  to 
find  the  mean  effective  pressure  by  means  of  an  indi- 
cator diagram,  as  shown  on  page  297.  If  it  is  imprac- 
ticable to  obtain  a  diagram  we  take  the  mean  average 
pressure  as  we  find  it  in  table  on  page  349,  which  is  49.4 
pounds,  or  50  pounds  in  round  numbers,  in  this  case. 
Multiply  the  same  by  the  area  of  the  piston  in  square 
inches  and  the  speed  of  the  piston  in  feet  per  minute, 
and  divide  the  product  by  33,000  (foot-pounds  of  horse 
power  per  minute.  See  table  on  page  347). 

The  area  of  piston  in  square  inches  we  find,  accord- 
ing to  rule  given  on  page  309,  equal  to— 

12*  X0.7854=144X  0.785=113.0, 
which  is  also  given  direct  in  table  on  page  314. 

The  piston  speed  is — 

30X,90°X2=450  feet  per  minute. 
us 

Hence  the  horse  power— 

113X450X50    , 

—33^0— =77  horse  power. 

This  is  the  indicated  horse  power,  the  net  effective 
horse  power  being  the  indicated  horse  power  less  the 
friction  of  the  engine. 

The  table  on  Corliss  engine,  on  page  340,  gives  the 
indicated  horse  power  of  an  engine  of  above  description 
at  54,  this  difference  being  probably  due  to  a  difference 
in  the  mean  effective  pressure  and  to  an  allowance  for 
piston  space  having  been  made  in  the  latter  case. 

WORK  OF  COMPRESSOR. 

Q.— What  is  the  work  of  compression  done  by  a 
double-acting  ammonia  compressor  9  inches  in  diameter, 
15  inches  stroke  at  70  revolutions  per  minute?  The  back 
pressure  is  28  pounds  and  the  condenser  pressure  115 
pounds. 

This  problem  is  calculated  on  the  same  principles  as 
the  foregoing  example;  but,  as  in  that  case,  the  proper 
way  is  to  obtain  the  mean  effective  pressure  from  an 
indicator  diagram.  If  we  use  the  table  on  page  298 
instead  we  find  the  mean  pressure  in  this  case  at  52.6 


368  MECHANICAL  REFRIGERATION. 

pounds.    The  area  of  piston,  by  table  on  page  314,  is 
G3.6  square  inches,  and  its  travel  per  minute  equal  to— 

2X70X15    1t.  „ 
—  j2  —  =116  feet; 

hence  the  work  done  by  the  compressor  is  equal  to— 


This  is  the  indicated  horse  power  of  the  work  done 
by  the  compressor.  In  order  to  find  the  indicated  horse 
power  (of  an  engine)  required  to  do  this  work  we  must 
add  to  the  above  the  work  required  to  overcome  the  fric- 
tion in  the  compressor  as  well  as  in  the  engine  itself. 

CALCULATION  OF  PUMP. 

Q.  —  How  many  revolutions  must  be  made  by  a  single- 
acting  pump  having  a  piston  of  4  inches  in  diameter  and 
12  inches  stroke  in  order  to  force  400  gallons  of  water  60 
feet  above  the  level  of  pump  per  hour,  and  what  will  be 
the  power  required  to  do  this  work  ? 

According  to  table  on  page  322  the  displacement  by 
this  pump  for  each  stroke  is  0.653  gallons  ;  hence— 

4.00 

-|jg-=  605  strokes; 

or,  in  round  numbers,  600  strokes  must  be  made  per  hour; 
and  as  the  pump  is  single-acting  this  corresponds  to  600 
revolutions  per  hour,  or  ten  per  minute.  The  work  done 
by  this  pump  in  lifting  the  water  may  be  calculated  the 
same  way  as  the  work  done  by  a  compressor,  by  simply 
inserting,  instead  of  the  mean  average  pressure,  the 
pressure  corresponding  to  a  water  column  of  60  feet  in 
height,  viz.  :  26  pounds  in  round  numbers,  as  per  table  on 
page  326. 

WATER  POWER. 

Q.—  1.  What  is  the  power  of  a  water  fall  twenty  feet 
high  and  300,000  cubic  feet  of  water  per  minute?  2. 
What  amount  of  coal  and  steam  respectively  would  give 
the  same  power  during  twenty-four  hours  ? 

In  accordance  with  page  108  one  cubic  foot  of  water 
weighs  62.5  pounds;  hence  by  using  rule  on  water  power 
given  on  page  43,  we  find  the  theoretical  power  of  the 
water  fall  in  question  equal  to— 


Of  this  theoretical  effect  may  be  utilized  30  to  75  per  cent 
by  water  motors,  according  to  construction,  etc.;  50  to 


APPENDIX  II.  369 

75  per  cent  by  turbines  ;  70  to  80  per  cent  by  water  press- 
ure engines  (generally  not  used  for  falls  less  than 
fifty  feet  in  height).  Taking  50  per  cent  as  a  safe  basis, 
the  actual  work  that  can  be  expected  from  the  fall  would 
be  equal  to — 

12,400  =  6^200  horge  power 

This  power  would  of  course  still  be  correspondingly 
reduced  if  the  mechanical  power  of  the  water  motor  had 
to  be  converted  into  electricity,  to  be  transmitted  to  a 
distant  locality,  there  to  be  converted  into  mechanical 
power  again.  Leaving  this  out  of  the  question,  and 
assuming  that  electricity  was  the  form  of  energy  wanted, 
we  find,  from  page  108  of  the  Compend,  that  from  fifteen 
to  thirteen  pounds  of  steam  will  produce  a  horse  power 
per  hour,  and  that  a  pound  of  average  coal  will  make 
about  eight  pounds  of  steam;  hence  a  horse  power  will 
require  not  over  two  pounds  of  coal  per  hour  with  a 
good  engine,  and  therefore  6,200  horse  power  may  be 
estimated  equivalent  to  6,200x24x2=297,600  pounds  of 
coal  in  twenty-four  hours. 

Allowing  fifteen  pounds  of  steam  per  horse  power, 
the  actual  power  of  the  water  fall  would  be  represented 
by  6,200x15=93,000  pounds  of  steam  per  hour. 

With  first-class  machinery  it  would  take  less  steam 
and  coal. 

MOTIVE  POWER  OF  LIQUID  AIR. 

Q. — What  is  the  amount  of  work  expressed  in  foot- 
pounds and  in  horse  power  that  can  be  done  by  one  pound 
of  liquid  air  while  expanding  or  volatilizing  at  the  con- 
stant temperature  of  70°,  this  being  the  average  atmos- 
pheric temperature  V 

According  to  page  260,  we  find  the  work,  Wi,  in  foot- 
pounds, which  can  be  done  theoretically  by  the  isothermal 
expansion  of  Fj,  cubic  feet  of  liquid  air  to  the  volume  of 
V  cubic  feet  and  the  pressure  P  (in  pounds  per  square 
foot)  after  the  formula— 

Wt  =  P  V  X  2.3026  by  y 

In  the  problem  on  hand  we  have  P  =  2,117  pounds. 
F"lf  the  volume  of  one  pound  of  liquid  air,  is  not  exactly 

TT 

known  but  1— ,  the  ratio  of  the  volume  after  and  before 


370 


MECHANICAL  REFRIGERATION. 


expansion,  is  about  800,  and  Vt  the  final  volume  of  one 
pound  of  air  in  cubic  feet  at  70°  F.  and  at  atmospheric 
pressure  is  equal  to  about  13.34  cubic  feet.  Hence  the 
formula  developes  into— 

^=2,117X13.34X2.3020  log.  800=188,800  foot-pounds. 
(Log.  800  being  equal  to  2.9031.  See  table  on  page  316.) 
In  order  to  express  this  effect  in  horse  power,  the 
time  in  which  the  pound  of  air  is  to  expand  should  be 
stated  also.  Assuming  that  it  takes  place  at  the  rate  of 
one  pound  of  liquid  air  expanding  per  minute,  the  horse 
power  would  be— 

188,800 
33  000  =         horse  power. 

This  is  the  theoretical  figure;  practically,  a  reduction 
would  have  to  be  made  for  friction,  etc. 

MOISTURE  IN  COLD  STORAGE. 

Q.— Assuming  that  34°  is  the  proper  temperature  for 
an  egg  storage  room,  what  is  the  proper  percentage  of 
moisture  which  it  should  contain,  and  how  should  the  wet 
bulb  thermometer  of  a  hygrometer  or  sling  psychrometer 
stand  in  order  to  indicate  that  percentage  of  moisture  ? 

According  to  Cooper  the  percentage  of  moisture  for 
cold  storage  rooms,  especially  for  eggs,  should  vary  with 
the  temperature  as  follows  : 


Temperature 
in  Degrees  F. 

Relative  Humid- 
ity, Per  Cent. 

Temperature 
in  Degrees  F. 

Rel'tive  Humid- 
ity, Per  Cent. 

28 
29 
30 
31 
32 
33 
34 

80 
78 
76 
74 
71 
69 
67 

35 
36 
37 
38 
39 
40 

65 
62 
60 
58 
56 
53 

Therefore  for  a  storage  temperature  of  34°  the 
moisture,  or  relative  humidity,  should  be  67  per  cent  (100 
per  cent  corresponding  to  air  saturated  with  moisture), 
and  by  referring  to  table  on  page  112  we  find  that  this 
corresponds  to  a  difference  between  the  dry  and  the  wet 
bulb  of  3.5°.  Hence  the  wet  bulb  thermometer  should 
show  34—3.5=30.5°. 

CARBONIC  ACID  VS.   AMMONIA. 

Q. — We  would  like  to  ask  you  for  some  information 
pn  ice  machines,  as  to  bow  the  carbonic  anhydride  ice 


APPENDIX  II.  371 

machines  are  in  comparison  with  the  ammonia  ice  ma- 
chines. The  carbonic  anhydride  machine  people  claim 
their  machine  far  superior  to  the  ammonia  machine. 
They  also  claim  that  carbonic  anhydride  has  more  freez- 
ing power  than  ammonia.  Is  this  in  accordance  with 
your  statement  in  Ice  and  Refrigeration  (see  same,  page 
247  of  Compend)  or  not? 

This  question,  which  was  directed  to  the  author  of 
the  Compend  personally,  would  indicate  that  his  state- 
ments with  reference  to  this  matter  were  misunderstood, 
or  at  least  apt  to  misconstruction.  The  superiority  of 
the  carbonic  acid  machine  would  of  course  tally  with 
4.300  and  3, 700  calories  per  horse  power;  but  these  figures 
were  quoted  by  the  author  as  phenomenal,  in  fact  as 
mere  claims,  unsupported,  so  far  at  least,  by  any  au- 
thentical  tests.  The  author  of  the  Compend  has  taken 
great  pains  to  find  any  tests  supporting  such  claims,  or 
to  find  a  carbonic  anhydride  machine  which  would  give 
some  such  results  in  actual  practice,  but  so  far  has  failed 
to  find  any.  On  the  contrary,  we  have  come  to  the  con- 
clusion that  the  results  of  the  practical  comparative 
tests  given  in  the  tables  on  page  247  of  Compend  have 
not  been  materially  exceeded  so  far,  at  least  not  with 
machines  without  expansion  cylinder,  and  only  such  are 
in  the  market  at  present,  as  far  as  we  know. 

As  a  result  of  the  present  status  of  the  theoretical 
aspect  of  the  questions  it  appears  that  at  temperatures 
of  70°  before  the  expansion  valve  and  20°  in  refrigeration 
coils  it  will  take  1.2  horse  power  in  a  carbonic  anhydride 
machine  to  produce  the  same  refrigeration  as  one  horse 
power  in  an  ammonia  refrigerating  machine.  Hence  the 
advantages  of  the  carbonic  acid  machine  must  be  looked 
for  in  other  directions  rather  than  in  that  of  greater  effi- 
ciency. 


372  MECHANICAL  REFRIGERATION. 

APPENDIX  III.— LITERATURE  ON  THER- 
MODYNAMICS, ETC. 


CL.-BOOKS. 

ATKINSON,  E.— Ganot's  Elementary  Treatise  on  Physics  Experk 
mental  and  Applied;  New  York,  1883. 

BERTHELOT,  E.— Mecanique  Chimique,  two  vols. ;  Paris,  1880. 

BEHREND,  GOTTLIEB.— Eis  und  KalteerzeugungsMaschinen;  Halle 
a.S.,  1888, 

CARNOT,  N.  L.  3.— Reflections  on  the  Motive  Power  of  Heat;  trans- 
lated byThurston;  New  York,  1890. 

CLAUSIUS,  R.— Die  Mechanische  Warmetheorie,  three  vols.;  Braun- 
schweig, 1891. 

CLARK  D.  KINNEAR.— The  Mechanical  Engineer's  Pocket  Book; 
New  York.  1892. 

COOPER,  MADISON.— Eggs  in  Cold  Storage;  Chicago,  1899. 

DUEHRING,  E.— Principien  der  Mechanic;  Leipzig,  1877. 

EWING,  S.  A.— The  Steam  Engine  and  Qther  Heat  Engines;  Cam- 
bridge, 1884. 

EDDY,  HENRY  T.— Thermodynamics;  New  York,  1879. 

FARADAY,  M.— Conservation  of  Force;  London,  1857. 

FISHER,  FERDINAND,  DR.— Das  Wasser;  Berlin,  1891. 

GRASHOF,  F.— Hydraulik  Nebst  Mechanische  Waermetbeorie;  Leip- 
zig, 1875. 

GAGE,  ALFRED  P.— A  Text  Book  on  the  Element  of  Physics;  Bos- 
ton, 1885. 

GIBBS,  WILLARD  J.— Thermodynamisches  Studien,  translated  by 
W.  Ostwald  ;  Leipzig,  1892. 

HELM,  G.— Energetik  DerChemischenErscheinungen;  Leipzig,1894 

HELM,  GEORGE.  —  Die  Lehfe  von  der  Energie;  Leipzig,  1887. 

HELMHOLTZ,  H.— Erhaltung  der  Kraft;  Berlin,  1847. 

HKLMHOLTZ,  H.— Wechselwirkung  der  Naturkraefte;  Koenigsberg 
J854. 

BERING,  C.— Principles  of  Dynamo  Electric  Machines;  New  York, 
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HIRN,  G.  A.— Equivalent  Mecanique  de  la  Chaleur;  Paris,  1858. 

HIRN,  G.  A.— Th6orie  Mecanique  de  la  Chaleur;  Paris,  1876. 

HOFF,  J.  H.  VAN'T.— Chemische  Dynamik;  Amsterdam,  1884, 

JOULE,  J.  P.— Scientific  Papers;  London,  1884. 

JEUFFRET,  E.— Introduction  a  la  Theorie  de  1'Energie;  Paris,  1883. 

KIMBALL,  ARTHUR  L.— The  Phj-sical  Properties  of  Gases;  Boston 
and  New  York,  1890. 

KENNEDY,  ALEX.  C.— Compressed  Air;  New  York,  1892. 

LEDOUX,  M.-Ice  Making  Machines:  New  York,  1879. 

LEAR,  VAN  J.  J.— Die  Thermodynamik  In  der  Chemie;  Leipzig,  1893 

LEASK,  A.  R.— Refrigerating  Machinery;  London,  1895. 

LEDOUX,  M.  —  Ice  Making  Machines,  with  Additions  by  Messrs. 
Denton,  Jacobus  and  Riesenberger;-New  York,  1892. 

LORENZ,  HANS.-NeuereKuehlmaschinen;  Muenchen  und  Leipzig; 

MARCHENA,  R.  E.  DE.— Machines   frigoriflques  a  gas  liquifiable; 

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APPENDIX  m.  573 

MAYER,  J.  R.— Berne  rkungen  ueber  das  Mechanische  Equivalent 
der  Waerme;  Heilbronn  und  Leipzig-,  1851. 

MAXWELL,  CLBRK  J.— The  Theory  of  Heat;  London,  1891. 

NYSTROM'S  Pocket  Book  of  Mechanics  and  Engineering;  Phila- 
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OSTWALD,  W.— Die  Energie  und  ihre  Wandlungen;  Leipzig,  1888. 

OSTWALD,  W.— Lehrbuch  der  allgemeinen  Chemie,  vom  Stand, 
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New  York,  1888. 

PUPIN,  M.  T.— Thermodynamics;  New  York,  1894. 
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RICHMOND,  GEO.— Notes  on  the  Refrigerating  Process  and  its  plac- 

in  Thermodynamics;  New  York,  1892. 
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TAIT,  P.  G.— Sketch  of  Thermodynamics;  Edinburgh,  1877. 
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THURSTON,  R.  H.— The  Animal  as  a  Machine  and  a  Prime  Motor 

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THURSTON,  R.  H.— Engine  and  Boiler  Trials  and  of  the  Indicator 

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THURSTON,  ROBT.  H.— Heat  as  a  Form  of  Energy;  Boston  and  New 

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THOMSEN,  I.— Thermochemische    Untersuchungen,    three    vols.; 

Leipzig,  1883. 
THOMSON,  SIR  W.— Lectures  on  Molecular  Dynamics;  Baltimore, 

1884. 

TYNDALL,  J.— Heat  Considered  as  a  Mode  of  Motion;  London,  1883. 
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VOHHBES,  GARDNER  T.— Indicating  the  Refrigerating  Machine; 
Chicago.  1899. 

WALD,  F.— Die  Energie  und  Ihre  Entwerting;  Leipzig,  1889. 

WALLIS-TAYLOR,  A.  J.— Refrigerating  and  Ice-Making  Machinery ; 
London,  1896. 

WOOD,  DE  VOLSON.— Thermodynamics,  Heat,  Motors  and  Refrig- 
erating Machines;  New  York,  1896. 

WAALS,  VAN  DER.— Die  Continuitat  des  Gasformigen  undFlussigen 
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ZENNER,  GUSTAVE.— Technische  Thermodynamik,  two  vols.;  Leip- 
zig, 1890. 


374  MECHANICAL  REFRIGERATION. 

b.-CATALOGUES. 

American  Insulating  Material  Manufacturing  Co.  (Granite  Rock 
Wool  and  Insulating  Materials),  St.  Louis,  Mo. 

Arctic  Machine  Manufacturing  Co.  (Ice  Making  and  Refrigerating 
Machinery,  Ammonia  compression  system),  Cleveland,  Ohio. 

Austin  Separator  Co.  (Oil  Separators),  Detroit,  Mich. 

Barber^A.  H.,  Manufacturing  Co.  (Ice  Making  and  Refrigerating 
Machinery,  Ammonia  compression  system),  Chicago,  111.' 

Buffalo  Refrigerating  Machine  Co.  (Ice  Making  and  Refrigerating 
Machinery,  Ammonia  compression  system),  Buffalo,  N.  T. 

Carbondale  Machine  Co.  (Ice  Making  and  Refrigerating  Machin-. 
ery,  Ammonia  absorption  system),  Carbondale,  Pa. 

Case  Refrigerating  Machine  Co.  (Ice  Making  and  Refrigerating 
Machinery,  Ammonia  compression  systemh  Buffalo,  N.  Y. 

Challoaer's,  Geo.,  Sons  Co.  (Ice  Making  and  Refrigerating  Machin- 
ery, Ammonia  compression  system),  Oshkosh,  Wis. 

Cochran  Company  (Ice  Making  and  Refrigerating  Machinery, 
Carbonic  anhydride  system),  Lorairi,  Ohio. 

De  La  Vergne  Refrigerating  Machine  Co.  (Ice  Making  and  Refrig- 
erating Machinery,  Ammonia  compression  system),  New  York 
City,  N.  Y. 

Direct  Separator  Co.  (Water  and  Oil  Separator),  Syracuse,  N.  Y. 

Farrell  &  Rempe  Co.  (Wrought  Iron  Coils  and  Ammonia  Fittings), 
Chicago,  111. 

Featherstone  Foundry  and  Machine  Co.  (Ice  Making  and  Refriger- 
ating Machinery,  Ammonia  compression  system,  and  Corliss 
Engines),  Chicago,  111. 

Frick  Co.  (Ice  Making  and  Refrigerating  Machinery,  Ammonia 
compression  system,  and  Corliss  Engines),  Waynesboro,  Pa. 

Gifford  Bros.  (Ice  Elevating,  Conveying  and  Lowering  Machinery), 
Hudson.  N.  Y. 

Gloekler,  Bernard  (Cold  Storage  Doors  and  Fasteners),  Pitts- 
burg,  Pa. 

Hall,  J.  &  E.,  Limited  (Ice  Making  and  Refrigerating  Machinery, 
Carbonic  anhydride  system),  London,  E.  C.,  England. 

Harrisburg  Pipe  and  Pipe  Bending  Co.,  Limited  (Coils  and  Bends, 
and  Ammonia  Fittings  and  Feed-water  Heaters),  Harrisburg,  Pa. 

aaslam  Foundry  and  Engineering  Co.  (Ice  Making  and  Refrig- 
erating Machinery,  Ammonia  absorption  system),  Derby, 
England. 

Hohmann  &  Maurer  Manufacturing  Co.  (Thermometers),  Roches- 
ter, N.  Y. 

Hoppes  Manufacturing  Co.  (Water  Purifiers  and  Heaters),  Spring- 
field, Ohio. 

Hoppes  Manufacturing  Co.  (Steam  Separators  and  Oil  Illumina- 
tors), Springfield,  Ohio. 

Kilbourn  Refrigerating  Machine  Co.,  Limited  (Ice  Making  and 
Refrigerating  Machinery,  Ammonia  compression  system), 
Liverpool,.  England. 


APPENDIX  III.  375 

Kroeschell  Bros.  Ice  Machine  Co.  (Ice  Making  and  Refrigerating 
Machinery,  Carbonic  anhydride  system),  Chicago.  111. 

MacDonald,  C.  A.'  (Ice  Making  and  Refrigerating  Machinery,  Am- 
monia compression  system),  Chicago,  111.,  and  Sydney,  N.  S*  W., 
Australia. 

Nason  Manufacturing  Co.  (Ammonia  and  Steam  Fittings),  New 
York  City,  N.  Y. 

Newburgh  Ice  Machine  and  Engine  Co.  (Ice  Making  and  Refriger- 
ating Machinery,  Ammonia  compression  system),  Newburgh, 
N.Y, 

Pennsylvania  Iron  Works  Co.  (Ice  Making  and  Refrigerating. 
Machinery,  Ammonia  compression  system),  Philadelphia,  Pa. 

Philadelphia  Pipe  Bending  Works  (Wrought  Iron  Coils  and  Bends), 
Philadelphia,  Pa. 

Remington  Machine  Co.  (Ice  Making  and  Refrigerating  Machinery, 
Ammonia  compression  system),  Wilmington,  Del. 

Ruemmeli  Manufacturing  Co.  (Ice  Making  and  Refrigerating  Ma- 
chinery, Gradirworks,  Ice  Cans,  Fittings,  etc.),  St.  Louis,  Mo. 

Siddely  &  Co.  (Ice  Making  and  Refrigerating  Machinery,  Ammo- 
nia absorption  system),  Liverpool,  England. 

Sterne  &  Co.  (Ice  Making  and  Refrigerating  Machinery,  Ammonia 
compression  system),  London,  England. 

Stevenson  Co.,  Limited  (Cold  Storage  Doors),  Chester,  Pa. 
Tight  Joint  Co.  (Ammonia  Fittings),  New  York  City,  N.  Y. 

Triumph  Ice  Machine  Co.  (Ice  Making  and  Refrigerating  Machin- 
ery, Ammonia  compression  system),  Cincinnati,  Ohio. 

Vilter  Manuiacturiog  Co.  (Ice  Making  and  Refrigerating  Machin- 
ery, Ammonia  compression  system  and  Corliss  Engines),  Mil- 
waukee, Wis. 

Vogt,  Henry,  Machine  Co.  (Ice  Making  and  Refrigerating  Machin- 
ery, Ammonia  absorption  System),  Louisville,  Ky. 

Vulcan  Iron  Works  (Ice  Making  and  Refrigerating  Machinery, 

Ammonia  compression  system),  San  Francisco,  Cal. 
Wheeler  Condenser  and  Engineering  Cq.  (Water  Cooling  Towers) , 

New  York  City,  N.  Y. 
Wheeler  Condenser  and  Engineering  Co.  (Auxiliary  Devices  for 

Increasing  Steam  Engine  Economy),  New  York  City,  N.  Y. 
Whitlock  Coil  Pipe  Co.  (Coils  and  Bends,  Feed-water  Heaters', 

Elmwood,  Conn. 

Wolf  Co.,  Fred  W.  (Ice  Making  and  Refrigerating  Machinery, 
Ammonia  compression  system),  Chicago,  111. 

Wolf  Co.,  Fred  W.  (Ammonia  Fittings  and  Ice  and  Refrigeratic^ 
Machinery  Supplies),  Chicago,  111. 

Wood,  Wm.  T.,  &  Co.  (Ice  Tools),  Arlington,  Mass. 

York  Manufacturing  Co.  (Ice  Making  and  Refrigerating  Machin- 
ery, Ammonia  compression  system,  York,  Pa. 


TOPICAL   INDEX. 


Absolute  boiling  point ...         60 

Pressure 44 

Zero "14,    49 

Zero,  change  of..... 84 

Absorber,  cleaning  of 291 

High  pressure  in. 291 

Operating  the 291 

The .235 

Water  required  for 228 

Absorption   and    compres- 
sion, efficacy  compared.  231 

Absorption,  heat  added  and 
removed  in  ... ...  .223,  224,  225 

Absorption  machines 86 

Capacity  of  (example)  ....  359 

Construction  of .......  232,  239 

Heat  and  steam  required 

(example) 359 

Miscellaneous    attach- 
ments  237.  238 

Tabulated  dimensions. . . .  239 

Absorption  of  gas 50 

Absorption  plant,  ammonia 

required  for 284 

Charging  with  rich  liquor  285 

Installation  of 283 

Charging  of 283 

Leaks  in 28S 

Management  of. 283,  295 

Overcharging  of 284 

Overhauling  of        2H8 

Permanent  gases  in    286 

Recharging  of 285 

Test  of 305 

Absorption  system,  actual 
and  theoretical  capacity 

of 230 

Ammonia,  required  in.227,  228 
Boil  over,  remedy  for  ...'.  290 
Correcting  ammonia  in  . ;  290 

Cycle  of 222 

Heat  of  poor  liquor ,  226 

Heat  removed  in  absorber  225 
Heat  removed   in  con- 
denser   225 

Liquid  pump  in 224 

Negative  head  of  vapor   .  227 

Operation  of  cycle 222 

Poor  liquor 224 

Rich  liquor  to  be  circu- 
lated  224 

Syphoning  over 289 

The 222,  239 

Working  of  same 223 

Absorption  vs.  compression 

231,  238 

Acetylene  for  refrigeration  254 


Adhesion g 

Adiabatic  changes  .......48.    63 

Affinity,  chemical 8%    35 

Air  machines 85.255,  261 

Air,  circulation    in   meat 

.   rooms         215 

Air,  compressed,  use  of  .;..  260 
Friction  in  pipes  ( table)      260 
Air,etc.. liquefied  by  Linde's 

method .266,  2tf7.  268 

Air  refrigerating  machines    85 

Air  required  in  combustion    30 

Saturated  with  moisture.  110 

Air  thermometer  76 

Air,  velocity  of .'.  187 

Alcoholometers,  compar- 
ison of  ( table) 323 

Ale    breweries,    refrigera- 
tion for 206,  207 

Ammonia,  anhydrous yi 

Boiling  point  of 103,  104 

Density  of 92 

Forms  of,  properties" of  '. '.    91 
Heat  by  absorption  (ex- 
ample)    358 

In  case  of  fire.... 276 

Latent  and  external  heat 

of i ; .    93 

Pressure    and     tempera- 
ture          9,'     !»4 

Properties  of 91 

Properties  of  saturated  . 

93,94,329,  331 

Refrigerating   effect    per 

cubic  foot  ( table)  -..'. 124 

Refrigeration    per   cubic 

foot  (tables) 124.  125 

Required  for  compression 

plant 275 

.Solubility  of,  in  water 

100,101,  102 

Specific  heat  of 92 

Specific  volume  of  liquid 

93,    94 

Table  of  properties  of  sat- 
urated   329,  331 

Temperature    in    expan- 
sion roil 115 

Tests  for 103,  104 

To  be  circulated  in  twen- 
ty-four hours  (table)  ...  124 
Van  der  Waals'  formula 

lor 95,    96 

Vapor,      superheated 

(table) 90,  311 

Waste  of,  in  compression.  275 
Wei glit  and  properties  of 
(tabulated)  <i;j     94 


TOPICAL  INDEX* 


377 


Ammonia  absorption,  heat 

generated  by  101,  102 

Ammonia   and   carbonic 
acid  system,  comparison 

of 246,  247 

Ammonia  charge,  fortify- 
ing same  (example) 353 

Ammonia  compression,  effi- 
ciency of  (table) 348 

Ammonia  compression  sys- 
tem, cycle  of 114 

General  features  of  114 

Ammonia    compressor, 

horse  power  for 133 

Ammonia  liquor,  kinds  of . .  287 
Properties  of  (table) 97, 98,  99 
Strength  of  (tables)97, 100,  101 

Ammonia  machines ; . .    88 

Ammonia  or  liquor  pump. .  237 
Ammonia  pump,  packing  of '292 

Analyzer,  the 233 

Anhydrous  ammonia  for 
recharging    absorption 

.    plant 285 

Apples,  cold  storage  Of 191 

Approximations,     useful% 

numbers  for. '338 

Aqua  ammonia,  kinds  of .. .  287 

Area  of  circles 314 

Argon,  physical  properties 

of . ..- 272 

Atomicity 33,    34 

Atoms., 5,     8 

Chemical 33 

Attemperators 206 

Size  of 206 

Sweet  water  for 207 

Avogadro's  law 53 


Breweries,  direct  refriger- 
ation for 209 

Refrigeration  for  .... .....  203 

Brewery,  piping  of  rooms 

in...... 204,  205 

Plants,  actual  installa- 
tions..   211 

Refrigeration;  objects  of, 
estimate  of  ,4. ...........  197 

Site.:... ..; 210 

Storage  rooms,  refriger- 
ation of. :.... 2Q1,  202 

Brewing  and  ice  making  .. .  210 
Brewery  equipment  of  fifty 

barrels 211 

Brine  agitator  .....  148 

Brine,  circulation  in  tank...  161 

Circulation,  pipe  for. 137 

From  chloride  of  calcium  142 

Preparing  of 140 

Simple  device  for  making  141 
Strength  of  (table). . . .140,  141 
Brine  circulation  vs.  direct 

expansion 142,  143 

Brine  coils,  cleaning  of 2H4 

Brine  pump 140 

Brine  system 137 

Brine  tank,  arrangement  of 

146,  147 

Leaks  in 293 

Operatic^  of 293 

Brine  tanks  and  coils,  di^ 

mensions  of  (table ) 187 

Brine  tanks,etc..toainting  of  282 

Brine  tanks,  piping  of 137 

British  thermal  unit.... 14 

Butter,  etc.,   temperature, 

etc.,  for  storing  of 193 

Freezing  rates  for 336 

By-pass  128 


Back  pressure 277,  278 

Barometers,  comparison  of 

(table) 45 

Battery  generator  or  retort  230 

Bamne  scales , 100 

Baum6  scale    and    specific 

gravity  (table)..   ..: 344 

Beds  and  refrigeration 219 

Beef,  specific  heatof  (table)  182 

Beer  chilling  devices 208 

Belting,  horse  power  of 324 

Blood  charcoal  filter 164 

Body 6 

Boilers,  description   of 

(table).. 337 

Heating  area  of  steam  ...  108 

Primingof 108,  109 

Horse  power  of   heating 

surface 328 

Boiling  point,  difference  in, 

elevation  of.. —    51 

Of  liquids 350 

Boil    over    in    absorption, 

remedy  for 290 

Boneblack  filter.; .....:  164 

Bonestink,  taint 215 

Taint,  stink,  testing  for  ..  216 
Books  on  refrigeration,  etc. 

372,  873 

Boyle's  law 44 


Cabbage,   specific   heat  of 
(table) 182 

Calculation  of  indicator 
diagram i ....  297 

Calculation  -of  pump  (ex- 
ample)   368 

Calculation  of  refrigerator 
for  cold  storage  rooms. 
180,  181,  182,  183 

Caloric,  French 15 

Can,  system  for  ice;  making, 
sizes  of 144 

Capacity,    maximum    and 

actual,  commercial 301 

Nominal  compressor,  ac- 
tual (table) ... 302 

Capacity  of  absorption  ma- 
chine (example) 359 

Capacity  of  absorption  sys- 
tem . ..t, .. 230 

Capacity  of  tanks  in  barrels 
(table).....1 326 

Capacity,   .commercial,    of     - 

compressor 302 

Refrigerating,    of     com- 
pressor (examples).  .356,  357 

Refrigerating,  unit  of .   90 

Theoretical,  correct  basis 
for ......  303 


378 


TOPICAL  INDEX. 


Capillary  attraction 60 

Carbon    dioxide,    physical 

properties  of 272 

Carbonic  acid  and  ammonia 

system,  comparison 

246,247,  371 

Carbonic  acid  machine.  340,  247 
Application  of,  efficiency 

of 244 

General  considerations. . .  240 
Joints,  strength  and  safe- 
ty . 244 

Theory  and  practice 245 

Carbonic   acid   plant,   con- 
struction of..'. 242 

Evaporator,  safety  valve.  243 
Carbonic  acid,  properties  of. 

(table) 240,  241 

Volume  of  (example)..  ..  366 
Carbonic  oxide,  physical 

properties  of 273 

Garnet's  ideal  cycle 69 

Catalogues  of  refrigerating 

machinery,  etc 874 

Ceilings,  dripping 294 

Cell  ice  system 167 

Changes,  adiabatic,  isother- 
mal     63 

Isentropic 77 

Isothermal,  adiabatic  ....    48 
Charge  of  ammonia  in  ab- 
sorption (example) 358 

Charging      of     absorption 

plant 283 

Charging    of    compression 

plant 273 

Cheese,  temperature,  etc., 

for  storing 194 

Chemical  affinity 8 

Chemical  combination.heat 

of. 33 

Chemical  heat  equation ....    35 

Chemical  symbols 33 

Chemical  works,  refrigera- 
tion in 220 

Chicken,   specific   heat   of 

(table) 183 

Chilling  meat 215 

Chilling  of  wort,  devices  for  208 

Chimney  and  grate "39 

Chloride  of  calcium,  prop- 
erties   of     solutions 

(table) 142 

Solutions  of  (table) 345 

Chloroform    manufacture, 

refrigeration  in 230 

Chocolate  and  cocoa  works, 

refrigeration  in 220 

Chocolate  making 220 

Circles,  area  of  (table)....,  314 
Circle,  properties  and  men- 

.     suratives  of. •. 310 

Circulating  medium,  choice 

of  .comparison  of  ( table )    89 

Refrigerating  effect  of...  115 

Combustion,  spontaneous,.  ,  38 

Circulation,  forced 187 

Cleaning  brine  coils 294 

Cleaning  of  absorber 291 

Cleaning  of  condenser.coils, 
etc 281 


Clearance,  excessive 299 

Marks 280 

Of  compressor 117,  118 

Clear  ice,  devices  for  mak- 
ing  ,  167 

Prom  boiled  water 157 

From  distilled  water 158 

Coal 38 

Evaporation   power   of 

(example) 354 

Evaporative  power  of..  38,  108 
Steam  making  power  of..  108 

Cohesion  (.table) 7 

Coils,  cleaning  of 281 

In  absorption  machine, 
corrosion  of,  economiz- 
ing of 287 

In  retort  or  generator. . . .  233 

Removing  ice  from 295 

Size  of  expansion.  133, 134,  136 

Coils  in  brine  tank  (table).  137 
Top  and  bottom  fed 294 

Coke i 38 

Cold    storage,   calculation 
of     refrigeration     for 

, 180,181,  182,  183 

Doors 179,  180 

Etc.,  usages  in 837 

Examples;  estimates 360 

Houses,  refrigeration  re- 
quired for . '. 174,  J79 

Moisture  in....; 184,185 

Moisture  in  (example) 370 

Of  apples,  of  vegetables, 

of  liquors 191 

Of  butter - 193 

Of  cheese 194 

Of  eggs 194 

Of  fermented  liquors 191 

Of  fish 192 

Of  grapes 190 

Of  lemons.... -..  190 

Of  milk.. 194 

Of  miscellaneous  goods. . .  198 

Of  onions 189 

Of  oysters 192 

Of  pears 190 

Of  vegetables 191 

Piping  for 176, 177,  361 

Temperatures I88k  196 

Ventilation  in 186 

Cold     storage     rates     (by 

month) 333,  334 

Terms  and  payment  of...  337 

Cold   storage   rooms,   con- 
struction in  brick  and 

tiles,  etc. 167   170 

Construction  of 168-173 

Description  of ,. iga 

Doors  for... 179 

Fireproof  wall  and  ceiil 

ing _ 170 

Piping  of 172 

Refrigeration  required  "  173 
Ventilation  of.....  ISQ 

Combustion '    35 

Air  required  for 86 

Gaseous  product  of 37 

Commercial     capacity    of 
compressor 303 

Comparison  of  compressor 
data  (table) 804 


TOPICAL  INDEX. 


379 


Comparison  of  refrigerat- 
ing fluids 248 

Compensated  transfer 72 

Compound  compressor 125 

Compressed  air  cycle, equa- 
tion of,  efficiency  of,  258,  259 
Friction      of,      in     pipes 

(table) 260 

Compressed    air   machine, 

actual  performance  of.  259 
Calculation  of  refrigera- 
tion   256,  267 

Compression  and  cooling.  256 

Cycle  of  operation 255 

Limited  usefulness 261 

Refrigeration  work. ......  258 

Theoretical  efficiency....  260 

Compressed  air,  uses  of —  260 

Compression,  heat  of 46 

Compression  machine 87 

Compression  of  gases 46 

Compression     plant,     am- 
monia required  for 275 

Charging  of 273 

Efficiency  of  (table) 278 

Installation  of  273 

Operation     of,    mending 

leaks 274 

Permanent  gases  in 279 

Proving  of 273 

Compression   system,  per- 
fect  , ....    88 

Compression  vs.  absorption 

... 231,  238 

Compression,  waste  of  am- 
monia in 276 

Compressor 114 

Ammonia  in 11« 

Capacity  of 117 

Capacity,  nominal  (table)  302 

Clearance  in 117 

Commercial  capacity  of..  302 

Efficiency  of 122 

For  carbonic  acid  plant. .  242 

Friction  of 302 

Heat  in,  superheating  in..  116 

Horse  power  of —  119 

Horse  power  required  for  183, 
Lost  work,  actual  work, 

determination  of 121 

Lubrication  of 282 

Maximum  theoretical  ca- 
pacity of 303 

Mean  pressure  in  (table).  298 

Piston  area  .   120 

Piston,  packing  of 281 

Power  to  operate  same. . .  133 
Refrigerating  capacity  of 

118,  119 

Refrigerating  capacity  of 

(example) 366,  357 

Size  of 119 

Useful  and  lost  work  of 

.... 120,121 

Volume  of. 117 

Work  by  a  (example)  ....  367 

Work  of 116 

Compressor  data,  compari- 
son of  (table) 304 

Compressor  engine,    horse 

power  of 121 

Compressor  test,  table 
snowing  items  of. 306 


Condensation  in  steam  pipe 

21,  24,25,26, 

Condensation  of  steam 

Condenser,  cleaning  of ;  — 
Dimensions  of  (tables)... 
For  carbonic  acid  plant. . 

Heat,  removed  in 116, 

Hendrick's 

In  absorption,  water  re- 
quired by 

Open  air 

Pipe  required  for.  127, 129, 

Pressure 277, 

Pressure  on,  water  for . . . 

Submerged 

Surface,  amount  of 

The,  in  absorption 

Water,economizingof  228, 

Water,  recooling  ot 

Water,  rinsing  of 

Conductors  of  heat 

Constituents  of  water,  com- 
position of  (table) 

Continuous  conversion 

Contracts  for  refrigerating 

plants 

Convection  of  heat 23, 

Conversion,  continuous, 

maximum 

Of  heat 

Convertibility  of  energy.. . 

Of  heat,  rate  of .".... 

Coolers  for  wort,    how    to 

manipulate.. 

Special  device 

Cooler,  the,  in  absorption.. 
Cooling  of  wort,    machine 

for,  efficiency  in 

Refrigerating     required 

for 

Cooling  water  for  con- 
denser, amount  of  econ- 
omizing   

Cooling    .water     in     pipes 

(tables) 26,27, 

Cooling  wort  (example) 

Core  in  ice 

Corliss  engines,  dimen- 
sions of  (table ) 

Corrosion  and  economizing 

of  coils  in  absorption. . 
Cost  of  making  ice. .149, 154, 

Of  refrigeration 167, 

Cream,    specific     heat     of 

(table) 

Critical  condition... 

Critical  data 

Critical  data  (table) 

Critical  pressure   46, 

Critical  temperature 46, 

Critical  volume 46,47, 

Cryogene  for  refrigeration 
Cube  roots,  squares,  cubes. 

etc.  (table) 312 

Cycle,    ideal,    efficiency  of 

^ 66.67,.68, 

Of    absorption    machine, 

equation  of  same 

Of  operations,  reversible. 

Cylinders,  contents   of,    in 

gallons  and  cubic   feet 

(table) 


29 
2» 
281 
131 
243 
303 
132 

228 
129 
131 
278 
130 
126 
127 
234 
229 
129 
129 
20 

351 
64 

807 
24 

64 
62 
83 
67 


237 
199 


367 
16'-' 


340 


155 

295 


56 
57 
47 
47 
47 
60 
254 

313 

69 

222 
65 


322 


880 


TOPICAL  INDEX. 


Dairy,  refrigeration  in 218 

Dalton's  law 46,    52 

Data  of  test,  table  showing.  304 
Decorative   effects,  by  re- 
frigeration   219 

Defects  of  ice 162 

Defrosting  of  meat 216 

Density ,.      6 

Density  of 'ammonia 92,    94 

Development  of  heat.. .....    35 

Dew  point... no 

Different     saccharometers 

....  v 200,  201 

Dimensions,  of  absorption 

machine  (tabulated)....  239 
Of  absorption   machines 

(table) 239 

Of  condensers  (table)  ....  131 

Of  Corliss  engines... 340 

Of  energy,  units  of 79 

Of  extra  strong  pipe 352 

Of  distilling  plants 160 

Of  ice  making  tanks(table)  145, 

Of  pipe,  standard 136 

Direct  expansion  vs.  brine 

circulation 142,  143 

Direct     refrigeration     for 

breweries 209 

Disinfecting   cold    storage 

rooms 188 

Dissipation  of  energy 63,    81 

Dissociation , 52 

Distilled    water,    filtering,      . 

rebelling,  cooling 159 

Production,  condensation  158 
Distilleries,    refrigeration 

in ,.220 

Distilling    plant,   arrange- 
ment Of,  operation  of. . .  161 

Dimensions  of 160 

Doors  for  cold  storage  room  179 
Doors  for  storage  rooms  ...  179 
Double  extra-  strong  pipe, 
dimensions  of  (table)'. ..  338 

Dripping  ceilings.. 2>4 

Dry  air  for  refrigeration..  185 

Dryer  for  ammonia      143 

Drying,  air 112 

Of  egg  room,  etc 195 

Dry  vapors 50 

Duplex  oil  trap 133 

Dwellings,  refrigeration  of  219 

Dynamics 9,    43 

Dynamite  works,  refriger- 
ation in 218 

Dyne -..,...  7.  346,  347 

Dyne  centimeter 10 


Ebullition 51 

Economizing  of  water 293 

Efficiency,    of     absorption 

and  compression.. 231 

Of  absorption  system 231 

Of  ammonia  compression 

(table) 348 

Of  boiler  and  engine 305 

Of    compressed    air   ma- 
chines ...  ..260 


Efficiency  of   compression 

plant  (table) 278 

Of  ideal  cycle ....  66.  67,  68,    69 
Of  sulphuric  dioxide  ma- 
chine        250 

Relative,  of  fuels 350 

Eggs,  freezing  rates  of 337 

Temperature,     etc.,     for 
storing,   moisture,  etc., 

..194,  195 

Elementary  bodies 33 

Elementary  properties  (ta- 
ble)     34 

Elements,     properties     of 

(table) 34 

Energetics,  system  of,  mod- 
ern  -...    78 

Energy,  C.G.  S.,  units  of  ...     10 
Chemical,  of  distance,  of 

surface  of  volume 78 

Comparison   of    units   of 

(table) .- 346,  347 

Conservation    of,    trans- 
formation of,  kinetic  ...    10 
Continuous  conversion  of    83 
Dissipation  of,  radiant          81 
Dimensions  of.  units  of.        79 

Dissipation  of 10,  63,    81 

Factors,  capacity  of,  in- 
tensity of./. 79 

Free  and  latent,  charges 

of . 72,   73 

New    departure  of,    me- 
chanical, electric (    78 

Of  a  moving  body 10 

Of  gas  mixtures 63 

Of  motion,  kinetic 78 

Reversible  an  d  irrevers- 
ible     82 

Transformation  of 82 

Uniform  units  of 83 

Visible,  kinetic,  potential, 

mplecular  9 

Engine  and  boiler.efflciency 

of 305 

Engineering  and  refrigera- 
tion   221 

Engines,      dimensions      of 
standard  Corliss  (table)  340 

Pounding  281 

Water  required  for 123 

Entropy -72 

And  intensity  principle  ..     83 

And  latent  heat 77 

Increase  of 74 

Equalization  of  pipes 138 

Equation     of     compressed, 

air  cycle .258,  259 

Equilibrium  of  energy, arti- 
ficial     81 

Equivalent  units 61 

Equivalents  in  piping 136 

Erg; 10,  346,  347 

Estimates  and  proposals  for 

refrigerating  plants 306 

Ether  machine,  efficiency  of  251 

Properties  of 251 

Properties  of  hypotheti- 
cal  ; 11,    12 

Ethyl  chloride  machine 249 

Ethylene,  physical  proper- 
ties of 272 

Evaporating  water 28,    30 


TOPICAL  INDEX. 


Evaporation  power  of  coal 

(example) 354 

Evaporator    for    carbonic 

acid  plant 243 

Examples  on  natural  gas...  361 

Exchanger,  leak  in 288 

The,  in  absorption 236 

Expansion,  by  heat 17 

Co-efflcient  of  (table) 17 

Free,  latent  heat  of 48 

Of  ammonia 134 

Of  liquids 17 

Of  liquids  and  solids  by 

heat  17 

Top  and  bottom  feed 294 

Expansion  coils,  size  of 184 

Expansion  valve 133 

Experiments  on  wort  cool- 

ing(table) 352 

Explosive  bodies 36 

External  work  of  vaporiza- 
tion     62 

Extra  strong  pipe,  dimen- 
sions of  (table) 352 


Freezing  Rates,  terms  and 

payment  of 337 

Rooms  in  packing  houses, 
calculation  of  refriger- 
ation   213 

Tank,    arrangement    and 

construction  of 147 

Tank,  dimensions  of  (ta- 
ble)   145 

Tank,  pipe  in 146 

Tank,  size  of.. . 148 

Time  for  (table) 146,  149 

Friction,  of  gases 49 

Of  water  in  pipes  (table) 

327.  346 

Frigorific  mixtures  Stable ) .    32 
Fruits,     temperature     for 

storing  188,  189,  190 

,Fuel;  economizing  of 161 

Fuels,  heat  of,  combustion 

of  (table) 38 

Relative  efficiency  of 350 

Fusion,     latent     heat     of 
(table) 31,  332 


Factors  of   energy,  of   in- 
tensity and  of  capacity.    79 

Fall  of  heat 71 

Fermentation,  heat  by 200 

Heat  of 200,  205 

Heat  produced  by,  calcu- 
lation, rule  for  ...  .  • 200 

Removing  heat  of 207 

Filter,      boneblack,     blood 

charcoal ; 164 

For  distilled  water,  inter- 

mediate 160 

Filters,   number   required-, 
when  required.when  not  165 

Filtration,  dangers  of 163 

Fire  and  ammonia 276 

Fish  and  oysters,  tempera- 
ture lor  storing 192 

Fish,  freezing  rates  for  ....  336 

Specific  heat  of  (table) 182 

Flow,  of  liquid,  quantity  of    42 

Of  steam 109 

Of  water  in  pipes. 43 

Fluids 40 

Viscosity  of.... 40 

Foot-pound 8,  346,  347 

Force,  measurement  of -....      7 

Molecular 7 

Unitof 7 

Forced  circulation 187 

Forecooler  131 

Free,  energy,  changes  of  72,-  73 

Expansion 48 

Freezing  back 279 

Goods'; 183 

Time 146,  149 

Freezing    mixture,  capaci- 
ty of  (example)  354 

Mixtures 86 

Ot  meat 21* 

Rate  for  butter   336 

Rates  tor  eggs ?33f 

Rates,  in  summer,  for  fish, 
for  meats ....  336 


Gallons  contained  in  cylin- 
ders (table) 322 

Gas  and  vapor 60 

Gaseous  products  of  com- 
bustion   37 

Gas   •  equation,     Van     der 

Waals'  .;..: ...55,  58,  59 

Gas  mixtures,  energy  of 63 

Gases,  absorption  of 50 

Adiabatic  changes 48,  63 

And  liquids,  general  equa- 
tion  55,  58,  59 

Buoyancy  of 46 

Components    of,     specific 

heat  of 75 

Constitution  of 44 

Critical  data  (table ) 47 

Critical  pressure 46 

Critical  temperature... ..  46 

Critical  volume 46,  47 

Density  of 53 

Equation  of 55,  56 

Expanding  into  vacuum..  62 

Expansion  of 55. 

Free  expansion 48 

Friction  of,  in  pipes 49 

Internal  friction  of 54 

Isothermal  changes 48,  63 

I^atent  heat  of  expansion.  48 

Liquef action  of 46.  60 

Mixtures  of 46 

Perfect 49 

Pressure     and     tempera- 
ture of , 44,  53 

Properties  of  (table) 272 

Relation  of  volume,  pres- 
sure   and   temperature 

•    of 48,  49 

Solubility  j>f,    in    water 

.    (table) 339 

Specific  heat  of,  at  con- 
.    statit  volume  and  pres- 

'  Jsure S5 

Specific  heat  of  (table)....  '47 

Velocity  of  sound  in          .  49 

Weight  of 45 


382 


TOPICAL  INDEX. 


Gauges 45 

Gauge  pressure 44,  45 

Gay-Lussac's  law 55 

Generation  of  heat 35 

Generator,  battery 232 

Heat  required  for 327 

Still  or  retort,  size  of 

(table)  232 

Glue  works,  refrigeration 

in 7. 218 

Glycerine  trap  in  carbonic 

acid  plant 242 

Grains  and  milligtams  per 

gallon  (table)...... 351 

Grapes,  cold  storage  of 190 

Graphite  for  lubrication.. .  282 
Gravitation  7 


Hampson's  device  for  lique- 


Harvesting  ice 148, 

Head  of  water 

In  pressure  per  square 

inch  (table).. 

Hea^,  absorption  of  (table) 

Available  effect  of 

Capacity    

By  absorption  of  ammonia 
(example) 

By  chemical  combination 

By  different  fuels  (table). 

By  mechanical  means .... 

C.  G.  S.  unit  of,  capacity 
of .... 

Changes,  components  of.. 

Complicated  transfers  . . . 

Cond  ucti vitir  ( table ) 

Convection  or 23, 

Conversion  of 62,  64, 

Determination  of  specific 

Emission  of  (table) 22, 

Emitted  by  pipes 

Energy,  origin  of 

Energy,  transfer  of 

Engines 

Fall  of 

Generated  by  absorption 
of  ammonia 101, 

Generated  by  ammonia 
absorption  101, 

Generation  of 35, 

Latent 30, 

Latent  of  fusion  and  vola- 
tilization ( table ) 31, 

Leakage  of  walls  for  cold 
storage 170, 

Of  chemical  combinations 

Of  combination  (table) 
36,  37, 

Of  compression 

Of  fermentation 

Produced  by  fermenta- 
tion, calculation,  rule 

for 

Heat  leakage, of  buildings. . 
Heat,  radiation  and  reflec- 
tion of  (table) 

Radiation  of ..11,12, 

Sources  of 

Specific,  of  liquids(tables) 


149 


171 
33 

38 

46 

205 


300 
170 


Heat,  specific,  of  metals  and 

other  substances 16 

Specific,  of  victuals...  182,  183 

Specific,  of  water 16 

Transfer  of 18,  23,    24 

Transfer  from  a.it  to  wa- 
ter     30 

Transfer,  theory  of 22 

Transmission  of,  through 

plates 27,38,29,    30 

Unitof 14 

Useofspecific 16 

Weightof 77 

Heater,  the,  in  absorption.  336 
Heating  surface  of  boilers.  328 
-Helium,  physical  proper- 

tiesof 272 

Hop   storage    by  artificial 

refrigeration 211 

Hop  storage,  temperature 

for 210 

vHops,  storage  of 210 

Horse  power 8,  43,  346,  347 

Of  belting,  of  shafting  (ta- 
ble).... . 324 

Of  boilers..... 328 

For    ammonia  compres- 
sors    133 

Grate   surface  .  required 

for 108 

Of  steam  engine(example)  367 

Steam  required  for 108 

Of  waterfall  (example)...  368 
Hospitals,  refrigeration  of .  219 

Houses  for  storing  ice 150 

Humidity   in   air,  relative, 

absolute 110,111,  112 

Table 1 332 

In  atmosphere(tables).lll,  112 

Hydrodynamics 43 

Hydrogen,  physical  proper- 
ties of 272 

Hydrometers,    comparison 

of  (table) 40,    41 

Hydrostatics 43 

Hygrometers 112 

Hygrometry 1 10 


Ice,  after  plate  system..  148,  149 

By  cell  system 167 

Cans,  sizes  of 144 

Cost  of  making 154 

Cost  of  making  (tables)154, 155 
Devices  for  making  clear  167 
Factories,  cost  of  operat- 
ing (table) 154,  155 

Formation  of   properties 

of 105 

Handling  of. 153 

Heat    conducting    power 

of    ..- 152 

Harvesting  ot 148,  149 

Houses,  refrigeration   of 

150,  351 

Machines,  construction  of    86 
Machines,    measurement 

of  size  and  capacity 90 

Making,  amount  of  water 

required  for  same 128 

Making  and  brewing 210 

Making,  can  system 144 


TOPICAL  INDEX. 


383 


Ice  making  capacity 90 

Making  capacity,  exam- 
ples on 368 

Making^   cost  of  same, 

149,164,  155 

Making,  properties  of  wa- 
ter for    ... 157,168 

Making/plate  system.  148,  149 
Making,  systems  of,  capa- 
city of  plant 144 

Making  tanks,  dimensions 

of  (table). , 145 

Odor  of..^., 1«4 

Packing  of 151 

Quality  of .....156,  157 

Removing  from  coils .  295 

Rotten 165,  166 

Selling  of  . 152 

Shrinkage  of.... 152 

Specific  neat  of 107 

Storage  houses — .  150 

Storage  houses,  refriger- 

ationof 150,  151 

Storage  of  manufactured  149 

Taste  and  flavor  of.  . . 164 

Test  for  ... 166 

Weight  and  volume  of 153 

Withdrawal  and  shipping 

of - .,./. 152 

With  core 162,  163 

With  red  core 163 

-With  white  core ; 162 

India  rubber  works,  ref  rig- 

.  erationin •.  .< 320 

Indicator   diagram,   inter- 
pretation of 299-302 

Indicator  diagram 296,  297 

Inertia ...:...      9 

Inflammable  bodies 36 

Installations,   actual,    of 

brewery  plant 211 

Of  absorption  plant ^  283 

Of  compression  plant. . .  .  273 

Insulation 282 

Of  steam  pipes  (table ) 20 

Insulators  (table ) 19 

Intensity,  and  entropy  prin- 
ciple     83 

Principle,    compensation 

of... 80 

Internal  work  of  vaporiza- 
tion     52 

Isentropic  changes 77 

Isothermal  changes. . 48,    63 

Isothermal       compression, 
work  required  for ...259 


Joule....  846,  347 


Kilogrammeter 8 

Kinds  of  aqua  ammonia  or 

ammonia  liquors 287 

Kinetic  energy 9 

Kinetics,  molecular. 53 


Latent  energy,  changes  of. 
72,    73 

Latent  heat,  of  fusion  (ta- 
ble).,     31 


Latent  neat  of  solution.. 31,   32 

.  Of  vaporization 51 

Leakage  of  heat  in  build- 
ings   1TO 

Leak  in  plant  discovered  by 

soapsuds 273 

Lifting  of  heat  ( example ) . .  355 

Lignite r. 39 

Linde   liquid  (oxygen),  its 

uses : 271 

Linde's  method,  for  lique- 
faction of  air,etc.266, 267,  268 
Rationale  of ........... .267,  268 

Liquefaction  of  gases.  ..266,  272 

History  of.,. 266 

Liquefaction  of  vapors 52 

Liquefied    air    by   Linde's 

method ;.....;.... 266,  267,  268 
Liquefying  air,  by  Hamp- 

son's method ,  268 

By  other  methods 269 

Liquid  air,,  for  motive  pow- 
er, for  refrigeration.  ..  270 
Motive  power  of  ( example)  369 

Uses  for  same 270,  271 

Liquid  receiver - .  ISO 

In  absorption 235 

Liquids, 'buoyancy  of. 40 

Boiling  point  of 350 

Expansion  of 17,  18 

Flow  of., 42 

Pressure  of 41 

Specific  heat  of 16 

Surface  tension  of 43 

Useful  data  about.  ...  341,  342 

Velocity  of 42 

Viscosity  of 40 

Liquid  traps 143 

Liquor  or  ammonia  pump..  237 
Liquor  pump,  in  absorption  224 

Work  done  by 227,228 

Liquors,    temperature    for 

storing  (table) 191 

Leaking  valve   and   piston 

packing 300 

Leak  in  rectifying  pans 289 

Leaks,  in  absorption  plant, 

in  exchanger 288 

In  brine  tank 293 

Lemons,  cold  storage  of ....  190 
Localities,  temperature  in 

different  (table) 341 

Logarithms,  rules  for  using 

them 317 

Table  of,  use  of. .  ..315,  316,  317 
Lowest  cold   storage   tem- 
peratures   196 

Lubricating  of  compressor  282 


Malt  houses,  refrigeration 
of 211 

Management,  of  absorber.  ..291 

Of  aosorption  plant 283-295 

Of  compression  plant .  .273-282 
Of  refrigerating  plants. . .  295 

Manometers •.<, 45 

Marsh  gas,  physical  proper- 
tiesof 272 

Mass. 6 

Unit  of..,  6 


Materials,  specific  weight  of 
(tables) 319,320, 


321 


384 


TOPICAL  INDEX. 


Matter,  constitution  of 5 

General  properties  of  .V. .  5 
Solid,  liquid,  gaseous.....  5 

Maximum  conversion 64 

Maximum  convertibility...    83 

Maximum  principle 85 

Mean  effective  steam  pres- 
sure (tables) .348,  849 

Pressure  of    compressor 

(table) ...i 298 

Measures  and  weights  (ta-       - 

bles) 317,318,  319 

Meat,  cause  of  bonestink  of  216 

Chilling 215 

Effect  of  freezing  on.. 214,  217 
Freezing  from  within,"  de- 
frosting of..... 316 

Freezing  of,  storage  tem- 
peratures ( table) 214 

Mold  on,  keeping  of,  ship- 
ping of..., ..— .,.  217 

Rooms,  circulation  of  air 

W i ..,.^...215,  217 

Thawing  and   defrosting 

of , 216 

Time  of  keeping  of. .- 217 

Withdrawing  fromMstor-    - 

1  age Y>V.V...  31* 

Meats,  freezing  rates  for  ..  336 
Meat  Storage,  official  views 

on..,.:..... t 214 

Mechanisms , 11 

Megerg 10- 

Melting  points  ( table )  . . . . . .    31 

Mensuration,   of  circle, 
solids,  polyhedrons,  etc.  310 

Of  surfaces  (table ) 309 

Mercury  wells 298 

Metals,  conductivity  of  .^ ...    22 

Specific  heat  of 15 

Specific  weight  6*7 819-321 

Me thylic chloride  machine.  249 
Metric    and  U.   S.   weights 

and  measures  (table).:..  323 
-Measurement,     compari- 
son  .,,..  319 

Milk,  specific  heat  of  (table)  182 
Temperature,  e  t  c . ,  f  o  r 

storing ......;..  194 

Milky  ice 162 

Milligrams  and  grains  per 

gallon,  etc.  (table)..,...  351 
Minerals,    metals,    stones, 
specific  weight  of  (table) 

......319-321 

Miscellaneous  goods,   tem- 
peratures, etc.,  for  stor- 

.    age .( ...  196 

Miscellaneous  ref  r  i  g  e  r  a  - 

tion 218-221 

Mixed  vapors 52 

Mixtures,  frigorific  (table).    32 

Temperature  of .'.....    16 

Modern  concepts..'...  ......    83 

Modern  energetics — 78 

Moisture,  in   air,   absolute . 

determination  of 110 

In  air  (table) 332 

In  atmosphere  (tables) lllt  112 

In  cold  storage ,.  184J 

In  cold  storage  (example)  370. 
Relative,  in  cold  storage.  370 
Rules  for,  cold  storage, .. .  187 


Mold  on  meat 211" 

Molecular  dynamics .\.KM5U 

Forces 7 

Kinetic ...,:....    53 

Transfer  of  energy- .....  .    62 

Velocity. ?,..:.  ....    54 

Molecule 33 

Molecules ,    58 

Heat  energy  of..,....! 54 

Momentum- ^ 8 

Motion.. 7 

Laws  of.. „..:... 9 

Perpetual.. 82 

Motay  and  Rossi's  system  of 

•  refrigeration  . . . , 254 

Motive  power  of  liquid  air 
(example) 369 


N 


Natural  gas,  expansion,  re- 
frigeration, Work.  etc. 
, 361,362,  363 

Negative  specific  heat 76 

Nitric  oxide,  physical  prop- 
erties of.: ....  273 

Nitrogen,  physical  proper- 
ties of 272 

Noise  in  engine  or  pump, 
how  located.. ....  ..281 


Odor  of  ice lt>4 

Oil  trap. , 126 

Duplex  ........;.. 133 

Oil  works,  refrigeration  in.  218 

Onions,  cold  storage  of 189 

Operation   of  compression 

plant 274 

Optics .    io 

Overhauling  absorption 

plant...... ..' 238 

Oxygen,  physical  properties 

Of, .....i 279 

Oysters,   specific    heat    of 

(table) ...• 182 

Oysters  and  fish,  tempera- 
ture for  storage J92 


Packing   houses,    etc.,    re- 
frigeration for,  rule  for- 

•  calculation  . , 212,  213 

Freezing  rooms,  piping  of 

same ..'..:.  ..212,  213 

Packing  of  ammonia  pump,  292 
Packing  of  compressor 

piston -. 281 

Packing  of  ice 151 

Painting  brine  tanks,  etc..  X82 

Pascal's  law. . .  / 40 

Passage  of  heat. 64 

Pears,  cold  storage  of  .  ...    190 
Peltry,  refrigeration  of....  218 

Perfect  gases 47 

>  Equation  of 55 

Performance  of  ammonia 
and  carbonic  acid  svs- 

.  ,  tem :..  : 246,247 

Performance  of  compressed 
air  machines ,  259 


TOPICAL  INDEX. 


385 


Permanent  gases,  examples 

•on '..  .....354,365 

In  absorption  plant 288 

In  compression  plant 279 

Origin  of 280 

Perpetual  motion 82 

Pf erdekraf t 346,  347 

Photography,  artificial  re- 
frigeration in 218 

Physics,  subdivisions  of  —    10 
.Pictet's   liquid,    refrigera- 
tion by 252 

Pictefs  liquids,  anomalous 

behavior  of 252,  253 

Pipe,  dimensions  of,  double 

extra  strong  (table).   ...  339 
Extra  strong,  dimensions 

of 352 

For  condenser 130 

Rules  for  laying 138 

Dimensions  of  (table )?...  136 
Plow  of  steam  in  (table).  328 
Friction  of  water  in 

(table) 327,346 

Table  for  equalizing.. ....  138 

Transmission  of  heat 135 

Pipe   required    in    c  o  n- 

denser 127,  129,131 

Pipes,  dimensions  of  stand- 
ard  136 

Piping,  equivalents  in 136 

Piping  of  brine  tanks 137 

Pipingcold  storage  rooms..  172 
For, cold  storage  (exam- 
ples)    361 

Of  brewery  rooms,  rules    - 

." 204,  205 

Required  for  storage 

rooms  (tables) 174-178 

Rooms 134 

Rooms  in  packing  houses, 

etc 213 

Rooms,  practical  rules  for  135 

Pipe  line  refrigeration 221 

Plants,  specification  of.  306,  307 
Plate  and  can  system,  com- 
parison of 148, 149 

Plate  ice,  size  of 149 

Plate  system  for  ice  mak- 
ing  148,149 

Polygons,  surf  ace  of  (table)  309 
Polyhedrons,  mensuration  • 

of  (table) 310 

Poor  and  rich  liquor  (table 

pt  strength) 226 

Liquor,   heat  introduced 

by 226 

Liquor  in  absorption, 

strength  of 224.  225 

Pork.specificheat  of  (table)  182 
Poultry,  freezing  rates  for.  335 
And  game,  rate  of  freez- 
ing of  . 334,335 

Rates   for   storing    un- 
frozen   336 

Pound,  Fahrenheit 346,347 

Pounding   pumps   and  en- 
gines  281 

Power   required     for    am- 
monia compressor   .....  133 
Furnished    by  liquid   air 
(example).,,,,,.,. 366 


Power'  required    to   raise 

water  (table ) 326 

Unit  of 8 

Practical  examples 353-370 

Practical  tests  of  ammonia 
and  carbonic  acid  sys- 
tem   247 

Pressure  and  temperature 

of  gas. 19 

Pressure,    condenser    and 

back ,...: 277,278 

Critical 46,   47 

Gauge,  absolute 44 

Mean  effective,  of  steam 

(tables) 348,  849 

Mean,  in   compressor 

(table) 298 

Of  liquids 41 

Unit  of •.    44 

Principles  of  energy,  regu- 
lative, intensity 80 

Properties  of  ammonia 91 

Of  ammonia  liquor..  97.  98,   99 

Of  gases  ( table) 272 

Of    saturated     ammonia 

(table) :...329,331 

Of  sulphuric  dioxide 249 

Proposals  and  estimates 
for  refrigerating  plants  306 

Psychrometers. Ill 

Pumping  of  vacuum 273 

Pump,  calculation  df  (ex- 
ample.)  : 3fi8 

Pumps.discharge by  (table)  139 

Pounding 281 

Purge  valve:... 132 


Radiation  of  heat...  11, 12,  22,   23 

Rates  for  freezing,  in  sum- 
mer, for  fish  and  meats,  336 
Poultry,  butter,  etc..  ..334-337 

Rates  of  cold  storage  (by 
months 333,  334 

Rationale  of  Linde's 
method 267,268 

Recharging  absorption 
plant 285 

Rectifier,  the,  in  absorption, 
size  of  (table)  234 

Rectifying  pans,  leak  in ....  289 

Red  core  in  ice. - 162,  163 

Refrigerating  capacity, 
nominal,  actual,  com- 
mercial   302 

Refrigerating  capacity,  of 
compressor  (examples) 

...., • 356,  357 

Units  of,  British,  Ameri- 
can  , 308 

Refrigerating  duty,  exam- 
ples on 364,  365 

Refrigerating  effect 52 

Net  theoretical 117 

Per  cubic  feet  ammonia 
(table) 124 

Refrigerating  fluids,  com- 
parison of 248 

Refrigerating    machine,,, 
ideal,  efficiency  of *    71 


386 


TOPICAL  INDEX. 


Refrigerating   machinery, 
etc.,  catalogues,    price 

lists 373 

Testing  of 308 

Refrigerating  ma  chines,     . 

different  systems,85,86,8T,  88- 
Refrigeratiag  plant,  fitting 

up,  for,  test  of 296 

Estimates  and  proposals 

for,  contracts 306,  307 

Testing  of 296-308 . 

Refrigeration,  according  to 

Motay  and  Rossi 254 

And  engineering 221 

And  work,  by  natural  gas 

(examples) ..361,362,363 

By  cryogene.by  acetylene  254 

By  dry  air 185 

By  liquid  air 270 

ByPictet's  liquid 252 

By  sulphur  dioxide 249 

Calculation  of,   for  cold 

storage 180, 181, 182, 183 

Cost  of! 167,295 

Different  systems  of 103 

During  transit 218 

Etc.,  books  on 372,  373 

For  breweries :. .  197-211 

For  miscellaneous    pur- 

.    poses 217-221 

For  packing  houses,  etc., 

rule  for  calculation 213 

In  breweries,  distribution 

of 203 

in  chemical  works. .  ..;..  220 
In  chocolate  factories....  220 

In  dairies.... 218 

In  distilleries 220 

Indwellings 219 

In  dynamite  works  219 

In  general,  means  of  pro- 
ducing     85 

In  glue  works 218 

In  hospitals 219 

In  India  rubber  works —  220 

In  malt  houses 211 

In  oil  works 218 

In  soap  works 218 

In  storing  trees 218 

In  sugar  refineries. . . :  ...  220 
In  sulphuric  acid  works, 

soda  works 221 

Means  of  producing 85 

Of  brewery  storage  rooms 

201,202 

Of  photographic  supplies,  218 

Of  silk  worm  eggs 218 

Required    for  storage 

rooms  (tables) 174, 179 

Self -intensifying .265 

Transmission  of 135 

Uses  of  artificial 90 

Refrigeration  units,  differ- 
ences between  them....  308 
Relative   moisture   or  hu- 
midity (table) 112 

Retort,  heat  required  for. .  227 
Or  still  in  absorption,  coils 

in 232.333 

Reversible  changes •. .    82 

Reversible  cycle v.65,   88 

Refrigeration  in 89 


Rich  and  poor  liquor  (table 

of  strength) 

Rich  Ijquor,  amount  of,  to 

be  circulated ... 

Example  on. 

In  absorption,  strength  of 


Rooms,  construction  of,  for 

cold  storage.. 169, 170, 171, 172 
In  brewery,  piping  of  .204,  205 

Rotten  ice 165,  166 

Rules  for  laying  pipe 138 

Of  moisture  in  cold  stor- 
age  :...  187 

S 

Saccharometers.  compari- 
son of  (table) 202 

Different 201 

Safety  valve    in    carbonic 

acid  plant 243 

Salometer,  substitute  for, 

comparisonof 142 

Salt  cake,  decomposition  of, 

by  refrigeration -221 

Salt    solutions,  properties 

of ...  . 140 

Saturated  ammonia,  table 

of  properties  of 329-331 

Saturated  vapors 50 

Scale  in  coils  removed  by 

acid*....'.. 291 

Scales,   different,  of  ther- 
mometers  12,  13 

Self-intensifyingrefrigera- 

tion 265 

Shipping  provisions,  refrig- 
eration in •. .  219 

Silk  worm  eggs,  refrigera- 
tion of    218 

Site  for  brewery 210 

Skating  rinks 154,  156 

Skimmer 161 

Soapsuds  to  discover  leaks  273 
Solids,    mensuration    of 

(table) 310 

Solubility,  of  ammonia  in 

water  (table) 102 

Of  gases  in  water  ( tables  X339 
Solution,  latent  heat  of.. 31,   32 
Solutions,     of     ammonia, 
strength  and  properties 

(table) » 100,  101,102 

Of  chloride    of  calcium 

(table)..... 346 

Sound,  velocity  of 49 

Southby's  vacuum  machine  263 

Operation  of 264 

Space,  measurement  of 6 

Spe-cific   gravity  and 

^  Baume  scale  ( table)  —  344 
Specific      gravity,     deter- 
mination of 40 

Specifications  of  plants. 306,  307 
Specific  heat,  calculation  of  183 

Determination  of.  16 

Example  on 354 

Negative 76 

Of  ammonia 9J 

Of  beef 182 

Of  cabbage 182- 

Of  chicken 182 

Of  cream 182 


TOPICAL  INDEX. 


387 


Specific  heat  of  fish 


182 


"Of  gases  (table) 47 

Of  liquids 15 

Of  metals :.    15 

Of  milk 182 

Of  oysters J82 

Of  pork 182 

Of  veal 182 

Of  victuals.. 182 

Of  water,  of  ice,  of  steam.  107 

Of  wort  (table)...  197 

Useof. 16 

Specific  volume  of  steam...  107 

Specific  weight  0 

Of    materials    (tables) 

319,320,  321 

Spontaneous  combustion...    '66 
Square   and   cubic   roots 

»       (table)     312.  818 

Squares,  cubes,  roots,  etc. 

(table) ..312,  31S 

Statics 9 

Steam,    condensation    in 

pipes  (tables). .  .21,  24,  25,    86 
Condensation  of,  in  tubes.    29 
Economizing  of,  in  ab- 
sorption, amount  re- 
quired  229 

Steam  engine,  horse  power 

of  (example) 367 

Steam,  flow  of 109 

Flow  of.  in  pipes  (table)..  328 
Internal  and  external  heat 

of 106 

Latent  heat  of...  -. 106 

Steam  pipe,  condensation  in  21 

Insulation  of ,...20,    21 

Steam,  production  of,  work       < 

done  by 108 

Properties  of  (table) 107 

Saturated 105 

Specific  heat  of...., ^  106 

Specific  volume  of 107 

Total  heat  of ....-,  106 

Steam,  pressure  of  (table)..  107 
Steam  produced  per  pound 

of  coal... 108 

Steam    to    produce    horse 

power 108 

Steam,  volume  of 105 

St.  Charles'  law 44 

Stiff    valve   and   irregular 

pressure 800 

Storage  houses  for  ice,  con- 
struction, ante-room  of.  150 

Storage  of  hops  210 

Of  manufactured  ice  .149,  150 
Refrigeration  for,  piping 

for  (tables) 174-178 

Storage  rooms,  drying  of, 

etc 195 

Rent  of 337 

Ventilation 186 

Storage  rooms,  doors  for 

same 179 

Strength  of  brine  required  142 
Stuffing  box   for   carbonic 

acid  plant....;. 248 

Sublimation 62 

Sugar  works,  refrigeration     , 

Sulphuric  "acid,'  concentra- 
tion of,  by  refrigeration  221 


Sulphuric  dioxide  machine, 
useful  efficiency  of 250 

Sulphur  dioxide,  proper- 
ties of,  refrigeration  by  149 

Sulphuric  dioxide,  prop- 
erties (table) 250 

Refrigerating  effect  of 
(example) 356 

Superheated  ammonia  va- 
por (table) .  811 

Superheated  vapors 50 

Sup.er heating,  water  to 
counteract... 125 

Surface,  tension  of  liquids.    42 

Sweet  water 207 

For  attemperators 207 

Syphoning  over  in  absorp- 
tion plant  289 

Symbols,  chemical 88 


Tables  ( appendix  I) 809-352 

Tanks,  capacities  of,  in  bar- 
rels (tables) 325 

Taste  of  ice 164 

Temperature 12 

And  pressure  pf  gases          44 

Critical 46,    47 

Measuring  of  high 13,    14 

Of  mixtures 16,    17 

Comparison  of,  Fahr.  and 

Centigrade  (table) 343 

Etc.,  for  cold  storage..  188-196 
Etc.,  for  storing  butter. . .  193 
Etc.,  for  storing  cheese..  194 

Etc.,  for  storing  eggs 194 

For  hop  storage 210 

For  storing  fruit..  188,  189,  190 
For  storing  liquors  .  .....  191 

For  storing  milk 194 

For  storing  miscellaneous 

goods  (table) 196 

For  storing  oysters,  fish . .  198 
For  storing  vegetables...  191 

For  storing  meat 214 

In  different  localities 

(table)., 341 

Lowest,  for  cold  storage . .  196 
Temperatures  of  cellars...  205 

Tension,  of  vapors 60 

Of  vapors  in  air  (table). ..  Ill 
Of  water  vapor  (table)...  350 

Test  for  water,  for  ice 186 

Test  table,  showing  items 

of  compressor 806 

Testing     refrigerating 

plants 296-308 

More  elaborate,  data  of 

(table) i...  304 

More  exact,  of  absorption  305 
Results  of  absorption 

(table).:  30 

Tests,  for  ammonia 103,  10 

Theoretical  capacity  (maxi- 
mum)  303 

Therapeutics,  refrigeration 

in ; 219 

Thermal  units 848,  347 

Thermo-chemistry 10 

Thermodynamics 10,    61 

Thermodynamic  scale  of 
temperature 76 


TOPICAL  INDEX, 


Thermodynamics,  first  law 

of 61 

Second  law  of 61 

Thermometer,  Fahrenheit, 

Reaumur,  Celsius 12 

Thermometer  scales,  com- 
parison of  (table) -18 

Fahrenheit   and    Centi- 
grade,   comparison    of 

(table)., 343 

Thermometer,  scales  of....    II 

Time,  unit  of 8 

Time  for  f reezing.water.  146, 149 
Top  feed  and  bottom  feed 

expansion 294 

Transformation  of  energy.    82 
Transfer  of  energy,  artifl- 

»       cial  and  natural 81 

Transfer  of  heat,  compen- 
sated, uncompensated..    72 

Complicated 23,  24 

Prom  water  to  air 30 

Transmission   of  heat 
through  plates  of  metal 

..27,28,29,    30 

Transit,    refrigeration 

during 218 

Trees,  cold  storage  of 218 


Unit,  of  heat,  British  ther- 
mal     14 

Of  pressure . .    44 

Of  refrigerating  capacity.   90 

Units,  absolute.. ..;.     7 

British  and  American,  re- 
frigerating capacity  of.  308 

C.  G.S .............      7 

Derived .- 6 

Equivalent 61 

Fundamental 6 

Of  energy,  comparison  of 

(table  F 346,  347 

Units  of  refrigeration,  dif- 
ferences between 308 

Universe,  future  of 73 

United  States  and   metric 
measures  (comparison).  323 

Usages,  cold  storage 337 

Useful  data  about  liquids 

341,342 

Useful  numbers  for  approx- 
imations           338 

Uses  for  liquid  air 270,  271 

Uses  of  compressed  air  ....  260 


Vacuum 

High,  produced  by  liquid 

Vacuum '  machine*. ! !  ] 

Compound 

Efficiency  of 

Objection  to  sulphuric 
acid .. 

Operating  expense  of 

Refrigeration  by,  size  of 

261, 

Vacuum,  pumping  of 
Valve,  leaky,  stiff. ..,.'. '. '. '. I \ 

Lift 


271 

86 


268 

262 
273 


Van  der  Waals'  formula  for 

ammonia 95,96 

Vaporization 51,  113 

Latent  heat  of 61 

Vaporization  machines  ...    86 
Vapor  of  water,  tension  of 

(tables) Ill,  350 

Vapor,  boiling  points 51 

Vapors,  dry... 50 

Liquefaction  of,  mixture' 

of 52 

Saturated 60 

Superheated 50 

Tension  of 50 

Wet..., 50 

Veal,  specific  heat  of  (table)  182 
Vegetables,     temperatures 
for  storing  (table)  ...;..  191 

Velocity 8 

Of  air 187 

Ventilation  of  cold  storage 

rooms 186 

Volatilization,  latent  heat 

of  (table)..... 332 

Volt,  ampere 346.  347 

Volume  and  pressure  and 
temperature,   relations     _ 

of 4? 

Volume  and  weight  of  ice..  153 
Volume,  critical 46,    47 

W 

Walls  for  cold  storage,  heat 

leakage  of 170,  171 

Water  cooled  by  evapora- 
tion   120 

.Constituents,  composition 

of 351 

Economizing  of 293 

Evaporable  by  coal 38 

Evaporating  of 28,    80 

Expansion  and  weight  of, 
,    at  various  temperatures 

(table) 18 

Flow  of ,  in  pipes •.    43 

For  ice  making 157 

Friction  of,  in  pipes 

(tkble) 327,  346 

Head   of,   converted   in 

pressure  ( table ) 326 

Properties  of>  for  ice  mak- 
ing  157,166 

Required   to   raise   same 

(table) 326 

Required  for  refrigerat- 

ingplant ;...  128 

Required  to  make  ton  of 

ice 128 

Purity  of 113,  166 

Required  for  engine 123 

Specific  heat  of 106 

Steam,  etc .105 

Test  for,  requirements  of 

pure 166 

Volume  and  weight  at  dif- 
ferent temperatures  ...    18 
Volume  and  weight  of..;.  108 
Weight  and  expansion  of.    18 
Water  jacket  compressor..  124 
Water  motors,  useful  effect 
Of  . .  .368 


TOPICAL  INDEX. 


Water  power 43 

Calculation  of  (example)..  368 

Water  pressure —    42 

Water  vapor,  tension  of 

(table) 350 

Water  vapor,  table  of Ill 

Watt 346,  347 

Watt  hour 346,  347 

Weight 6 

Weight  of  heat 77 

Weights   and   measures, 

comparison  of 323 

Tables 317,  318,  319 

Weight,  specific 6 

Wet  compression 280 

Wet  vapors 50 

White  core  in  ice ...162 

White  or  milky  ice 162 

Wood  for  storage  rooms.  168,  171 
Woolen   goods,  pelts,  stor- 
ing of! 218 

Working  fluid  (influence  of)    67 


Work   of  compressor    (ex- 
ample)   367 

Work  to  lift  heat  (example)  355 

Work,  unit  of,  useful 8 

Work,  useful,  lost 19 

Wort  cooler,  dimensions  of  203 

Direct  expansion 204 

Wort   coolers,   special    de- 
vice   208 

How  to  m  anipulate 209 

Wort  cooling,  experiments 

in  (table) 352 

Wort,  cooling  of  (example)  357 
Wort  cooling,  machine  for, 

efficiency  in 199 

Wort  cooling,  refrigeration 

for,  calculation  for 198 

Wort,  specific  heat  of  (table)  197 


Zero,  absolute 14 


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